Annealed garnet electrolyte separators

ABSTRACT

Set forth herein are pellets, thin films, and monoliths of lithium-stuffed garnet electrolytes having engineered surfaces. These engineered surfaces have a list of advantageous properties including, but not limited to, low surface area resistance, high Li +  ion conductivity, low tendency for lithium dendrites to form within or thereupon when the electrolytes are used in an electrochemical cell. Other advantages include voltage stability and long cycle life when used in electrochemical cells as a separator or a membrane between the positive and negative electrodes. Also set forth herein are methods of making these electrolytes including, but not limited to, methods of annealing these electrolytes under controlled atmosphere conditions. Set forth herein, additionally, are methods of using these electrolytes in electrochemical cells and devices. The instant disclosure further includes electrochemical cells which incorporate the lithium-stuffed garnet electrolytes set forth herein.

BACKGROUND

A series of technological challenges must be overcome in order totransition the current energy economy, based on the consumption ofnonrenewable petroleum-based energy resources, into one in which humanssustainably produce, store, and consume renewable energy. With respectto automotive transportation, in particular, first and foremost amongthese challenges is the unmet need for renewable energy storage deviceswhich are suitable replacements for the internal combustion engine.Rechargeable batteries, and lithium (Li) rechargeable batteries inparticular, may be suitable substitutes in electric and hybrid-electricvehicles, but the high cost and limited performance of the conventionalbatteries available today has restricted large-scale market adoption ofthis technology. A key component of such batteries which limits itsperformance is the electrolyte.

In a rechargeable Li ion battery, Li⁺ ions move from a negativeelectrode to a positive electrode during discharge and in the oppositedirection during charge. An electrolyte physically separates andelectrically insulates the positive and negative electrodes while alsoproviding a medium for Li⁺ ions to conduct between the electrodes. Theelectrolyte ensures that electrons, produced when Li metal oxidizes atthe negative electrode during discharge of battery (e.g., Li↔Li⁺+e⁻),conduct between the electrodes by way of an external and parallelelectrical pathway to the pathway taken by the Li⁺ ions. If Li⁺ ions andelectrons recombine, as can happen when they share a conduction path,before both conduct separately from the negative to the positiveelectrode, no useful work is captured and Li dendrites may form and leadto thermal runaway. In some electrochemical devices, electrolytes may beused in combination with, or intimately mixed with, cathode (i.e.,positive electrode) active materials to facilitate the conduction of Li⁺ions within the cathode region, for example, from theelectrolyte-cathode interface and into and/or with the cathode activematerial.

Conventional rechargeable batteries rely on liquid-based electrolyteswhich include lithium salts dissolved in organic solvents (e.g., 1Msolutions of LiPF₆ salts in 1:1 ethylene carbonate:diethylene carbonatesolvents). However, these liquid electrolytes suffer from severalproblems including flammability during thermal runaway and outgassing athigh voltages. Solid state ion-conducting ceramics, such aslithium-stuffed garnet oxide materials, have been proposed as nextgeneration electrolyte separators in a variety of electrochemicaldevices including Li⁺ ion rechargeable batteries. When compared toliquid-based electrolytes, solid state electrolytes are attractive forsafety reasons, such as not being flammable, as well as for economicreasons which include low processing costs. Solid state lithium-stuffedgarnet electrolyte membranes and separators, in particular, are wellsuited for electrochemical devices because of their high Li⁺ ionconductivity, their electric insulating properties, as well as theirchemical compatibility with Li metal anodes (i.e., negative electrodes).Moreover, solid state lithium-stuffed garnet electrolyte membranes canbe prepared as thin films, which are thinner and lighter thanconventional electrolyte separators. See, for example, US PatentApplication Publication No. 2015/0099190, published Apr. 9, 2015 andfiled Oct. 7, 2014, entitled GARNET MATERIALS FOR LI SECONDARY BATTERIESAND METHODS OF MAKING AND USING GARNET MATERIALS, the entire contents ofwhich are incorporated by reference in its entirety for all purposes.When these thinner and lighter lithium-stuffed garnet separators areincorporated into electrochemical cells, the resulting electrochemicalcells are thought to achieve higher volumetric and gravimetric energydensities because of the volume and weight reduction afforded by thesolid state separators.

Certain solid state lithium-stuffed garnet electrolytes are known. See,for example, U.S. Pat. Nos. 8,658,317; 8,092,941; and 7,901,658; alsoU.S. Patent Application Publication Nos. 2013/0085055; 2011/0281175;2014/0093785; and 2014/0170504; also Bonderer, et al. “Free-StandingUltrathin Ceramic Foils,” Journal of the American Ceramic Society, 2010,93(11):3624-3631; and Murugan, et al., Angew Chem. Int. Ed. 2007, 46,7778-7781). However, to date and the best of Applicants knowledge, thereare no public disclosures of commercially viable thin film solid statelithium-stuffed garnet electrolyte separators or membranes for Lirechargeable batteries which have a sufficiently long cycle life at highcurrent densities and which conduct large amounts of lithium withoutforming lithium dendrites. There are also, to the best of Applicantsknowledge, no public disclosures of commercially viable thin film solidstate lithium-stuffed garnet electrolyte separators which have lowinterfacial and bulk ionic resistance and/or impedance.

Some of the contributors to bulk and interfacial resistance and/orimpedance in lithium-stuffed garnet electrolytes are impurities in thelithium-stuffed garnet oxide, which include but are not limited tosecondary phases other than a pure lithium-stuffed garnet oxide whichcan be found at either or all of the electrolyte's bulk, surface and/orinterface with other materials. Resistive secondary phases, e.g., Li₂CO₃on the surface or interface of a lithium-stuffed garnet solidelectrolyte are also a source of high impedance and poor cyclingperformance in lithium-stuffed garnet electrolytes. Previously,researchers mechanically processed lithium-stuffed garnet electrolytesto remove secondary phases from its surfaces. These techniques includedsanding or polishing the electrolyte surfaces to physically removesurface contaminants. However, these mechanical processing techniquesare cost-prohibitive for high volume production, tend to be destructiveto the material being processed, and tend not to prevent the formationof new surface contaminants or otherwise stabilize the mechanicallypolished surface.

There is therefore a need for improved thin film solid stateelectrolytes and, in particular, lithium-stuffed garnet electrolytes,which demonstrate commercially viable cycle life properties at high Li⁺current densities. What is needed in the relevant field is, for example,new thin film solid state ion-conducting electrolytes as well asprocesses for making and using these solid state electrolytes. Theinstant disclosure sets forth such materials and methods of making andusing the same, as well other solutions to other problems in therelevant field.

BRIEF SUMMARY

The present disclosure relates generally to components for lithiumrechargeable batteries as well as to lithium-stuffed garnet electrolytemembranes and separators for lithium rechargeable batteries. Some of theelectrolytes disclosed herein have low interfacial impedance, a reducedtendency for lithium dendrites to form therein or thereupon when used aselectrolyte separators in electrochemical cells, and/or haveadvantageous surface chemical compositions and features. Also providedherein are methods of making these solid-state electrolyte membranes andseparators including certain annealing methods for producing theaforementioned advantageous surface chemical compositions and features.The instant disclosure includes, in some examples, intermediatetemperature annealing methods, in inert or reducing environments, forremoving surface species, e.g., Li₂CO₃, which otherwise result in highimpedance and poor electrochemical performance in the electrolyte if notremoved. The instant disclosure includes, in some examples, serial heattreatment steps, in inert or reducing environments, for removing surfacespecies, e.g., Li₂CO₃, which otherwise result in high impedance and poorelectrochemical performance in the electrolyte if not removed.

In one embodiment, the instant disclosure sets forth a thin electrolytemembrane or separator, having top and bottom surfaces, wherein thelength or width of either the top or bottom surfaces is at least 10times the membrane or separator thickness, and wherein the membrane orseparator thickness is from about 10 nm to about 100 μm; wherein theelectrolyte bulk is characterized by the chemical formulaLi_(x)La₃Zr₂O₁₂ y(Al₂O₃), wherein 3≤x≤8 and 0≤y≤1; and wherein eitherthe top or bottom surface is characterized as having less than 1 μmlayer thereupon which includes a lithium carbonate, lithium hydroxide,lithium oxide, a hydrate thereof, an oxide thereof, or a combinationthereof. As used herein, the thickness of the layer on the membrane orseparator is only as thick or is thinner than the thickness of themembrane or separator, not including any layers thereupon. Herein, x andy are rational numbers.

As used herein, having less than 1 μm layer thereupon refers to asurface coating, or surface adhered or bonded layer, which is chemicallydistinct from the bulk material on which the surface coating is present.In some examples, this layer is a native oxide or an oxide whichspontaneously forms on the surface of the materials described hereinpost-synthesis and upon exposure to air.

In a second embodiment, the instant disclosure sets forth a method ofmaking a thin electrolyte membrane or separator, having top and bottomsurfaces, wherein the length or width of either the top or bottomsurfaces is at least 10 times the membrane or separator thickness, andwherein the membrane or separator thickness is from about 10 nm to about100 μm; wherein the electrolyte bulk is characterized by the chemicalformula Li_(x)La₃Zr₂O₁₂ y(Al₂O₃), wherein 3≤x≤8 and 0≤y≤1; and whereineither the top or bottom surface is characterized as having less than 1μm layer thereupon which includes a lithium carbonate, lithiumhydroxide, lithium oxide, a hydrate thereof, an oxide thereof, or acombination thereof. As used herein, the thickness of the layer on themembrane or separator is only as thick or is thinner than the thicknessof the membrane or separator, not including any layers thereupon. Insome examples, the method includes preparing a thin film lithium-stuffedgarnet electrolyte by calcining lithium-stuffed electrolyte garnetelectrolyte precursors in the presences of binders and or dispersants toprepare calcined thin films of lithium-stuffed garnet electrolytes andsubsequently sintering and annealing the thin films by heating the filmsa second or third time in a reducing or inert atmosphere and at elevatedtemperatures.

In a third embodiment, the instant disclosure sets forth methods ofreducing the area-specific resistance (ASR) of a lithium-stuffed garnetelectrolyte membrane or separator, wherein the method includes annealingthe membrane or separator by heating it after it is sintered in areducing atmosphere and at elevated temperatures. In some embodiments,the heating is between 500 and 750° C. and the reducing atmosphere isAr:H₂ or Ar or an inert atmosphere.

In a fourth embodiment, the instant disclosure sets forth anelectrochemical device which includes the electrolyte membranes and/orseparators set forth herein.

In a fifth embodiment, the instant disclosure sets forth methods ofusing electrochemical devices which include the electrolyte membranesand/or separators set forth herein, wherein the methods include bondinglithium metal to a surface of the electrolyte membrane or separatorusing a formation cycle.

In a sixth embodiment, the instant disclosure sets forth methods oflaminating, depositing, or bonding lithium metal onto an electrolytemembranes and/or separators set forth herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a transmission electron microscopy (TEM) image of Sample A(untreated)—a lithium-stuffed garnet prepared according to Example 2.The scale bar in the image is 0.5 μm.

FIG. 2 shows a TEM image of Sample B (treated annealed)—alithium-stuffed garnet prepared according to Example 2. The scale bar inthe image is 1.0 μm.

FIG. 3 shows an overlaid x-ray photoelectron spectroscopy (XPS) spectrafor lithium-stuffed garnet electrolyte membranes, Sample A and Sample B,prepared according to Example 2.

FIG. 4 shows an electron paramagnetic resonance (EPR) spectrum forSample B prepared according to Example 2.

FIG. 5 shows a scanning electron micrograph (SEM) of Sample B preparedaccording to Example 2.

FIG. 6 shows overlaid electrical impedance spectra for Samples(untreated) A and B (treated annealed).

FIG. 7 shows a reduced magnification of FIG. 6.

FIG. 8A shows electrochemical cycling data for a lithium-stuffed garnetelectrolyte membrane of Sample B, in a symmetric Li-metal cell, whichwas cycled at 2 mA/cm², for the first three cycles (FIG. 8A), and then 2mA/cm², for forty-six (46 days) at 130° C. (FIG. 8B). Each cycle passes20 μm of lithium in both directions (i.e. a half cycle is approximately4 mAh/cm²).

FIG. 9 shows an overlaid FT-IR spectra for Sample A (untreated) and B(treated annealed).

FIG. 10 shows Raman spectra for Samples A and B prepared according toExample 2.

FIG. 11 shows a plot of the survival electrochemical cells as a functionof failure current density (mA/cm²).

FIG. 12 shows a plot Weibull cumulative failure as a function of currentdensity.

FIG. 13 shows an rectangular shape

FIG. 14 shows a disc shape.

The figures depict various embodiments of the present disclosure forpurposes of illustration only. One skilled in the art will readilyrecognize from the following discussion that alternative embodiments ofthe structures and methods illustrated herein may be employed withoutdeparting from the principles described herein.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the presented concepts. Thepresented concepts may be practiced without some or all of thesespecific details. In other instances, well known process operations havenot been described in detail so as to not unnecessarily obscure thedescribed concepts. While some concepts will be described in conjunctionwith the specific embodiments, it will be understood that theseembodiments are not intended to be limiting.

The following description is presented to enable one of ordinary skillin the art to make and use the invention and to incorporate it in thecontext of particular applications. Various modifications, as well as avariety of uses in different applications will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to a wide range of embodiments. Thus, the inventions hereinare not intended to be limited to the embodiments presented, but are tobe accorded their widest scope consistent with the principles and novelfeatures disclosed herein.

In the following detailed description, numerous specific details are setforth in order to provide a more thorough understanding of the presentinvention. However, it will be apparent to one skilled in the art thatthe present invention may be practiced without necessarily being limitedto these specific details.

All the features disclosed in this specification, (including anyaccompanying claims, abstract, and drawings) may be replaced byalternative features serving the same, equivalent or similar purpose,unless expressly stated otherwise. Thus, unless expressly statedotherwise, each feature disclosed is one example only of a genericseries of equivalent or similar features.

Please note, if used, the labels left, right, front, back, top, bottom,forward, reverse, clockwise and counter clockwise have been used forconvenience purposes only and are not intended to imply any particularfixed direction. Instead, they are used to reflect relative locationsand/or directions between various portions of an object.

General Description

Though solid state electrolytes possess a host of theoreticaladvantages, there exists a need for improvements in the chemistry,processing and engineering of these electrolytes and their surfaces andinterfaces with lithium metal in order to make them more commerciallyviable for use in electrochemical cells. One of the major problemsassociated with electrolytes is that researchers have had difficultycontrolling the surface chemistry of for these electrolytes to operatein commercial devices. As an example, surface contamination by Li₂CO₃and/or LiOH is thought to be detrimental to the performance of theseelectrolytes. These species may block fast charge transfer kinetics atthe surface of the electrolyte and lead to high interfacial resistance.Other minor impurity phases at the surface, e.g. LiAlO₂ may also lead tohigh interfacial resistance. See, for example, Sharafi, Asma, et al.Journal of Power Sources 302 (2016) 135-139. See, for example, Cheng,L., et al., “Interrelationships among Grain Size, Surface Composition,Air Stability, and Interfacial Resistance of Al-Substituted Li₇La₃Zr₂O₁₂Solid Electrolytes,” ACS Appl. Mater. Interfaces, 2015, 7 (32), pp17649-17655, DOI: 10.1021/acsami.5b02528; Cheng, L., et al., ACS Appl.Mater. Interfaces, 2015, 7 (3), pp 2073-2081, DOI: 10.1021/am508111r,doi/abs/10.1021/am508111r; and Cheng, L., et al., Phys. Chem. Chem.Phys., 2014, 16, 18294-18300, DOI: 10.1039/C4CP02921F.

I. Definitions

As used herein, the term “about,” when qualifying a number, e.g., 15%w/w, refers to the number qualified and optionally the numbers includedin a range about that qualified number that includes ±10% of the number.For example, about 15% w/w includes 15% w/w as well as 13.5% w/w, 14%w/w, 14.5% w/w, 15.5% w/w, 16% w/w, or 16.5% w/w. For example, “about75° C.,” includes 75° C. as well 68° C., 69° C., 70° C., 71° C., 72° C.,73° C., 74° C., 75° C., 76° C., 77° C., 78° C., 79° C., 80° C., 81° C.,82° C., or 83° C. For example, evaporating a solvent at about 80° C.includes evaporating a solvent at 79° C., 80° C., or 81° C.

As used herein the phrase “about 1 to about 600 minutes,” refers to therange 0.1 to 1.1 to 540-660 minutes and the minute values therebetween.As used herein the phrase “about 10 μm to about 100 μm” refers to therange 9 μm-11 μm to 90 μm-110 μm and the integer values therebetween. Asused herein the phrase “about 500° C. to about 900° C.,” refers to therange 450° C.-550° C. to 810° C.-990° C. and the integer temperaturevalues therebetween.

As used herein, the term, “Ra,” is a measure of surface roughnesswherein Ra is an arithmetic average of absolute values of sampledsurface roughness amplitudes. Surface roughness measurements can beaccomplished using, for example, a Keyence VK-X100 instrument thatmeasures surface roughness using a laser.

As used herein, the term, “Rt,” is a measure of surface roughnesswherein Rt is the maximum peak height of sampled surface roughnessamplitudes.

As used herein, “selected from the group consisting of” refers to asingle member from the group, more than one member from the group, or acombination of members from the group. A member selected from the groupconsisting of A, B, and C includes, for example, A only, B only, or Conly, as well as A and B, A and C, B and C, as well as A, B, and C.

As used herein, the phrases “electrochemical cell” or “battery cell”shall mean a single cell including a positive electrode and a negativeelectrode, which have ionic communication between the two using anelectrolyte. In some embodiments, the same battery cell includesmultiple positive electrodes and/or multiple negative electrodesenclosed in one container.

As used herein, a “binder” refers to a material that assists in theadhesion of another material. Binders useful in the present inventioninclude, but are not limited to, polypropylene (PP), atacticpolypropylene (aPP), isotactive polypropylene (iPP), ethylene propylenerubber (EPR), ethylene pentene copolymer (EPC), polyisobutylene (PIB),styrene butadiene rubber (SBR), polyolefins,polyethylene-co-poly-1-octene (PE-co-PO), PE-co-poly(methylenecyclopentane) (PE-co-PMCP), stereoblock polypropylenes, polypropylenepolymethylpentene copolymer, acrylics, acrylates, polyvinyl butyral,vinyl family, cellulose family, polyethylene glycol, resins, polyvinylalcohol, polymethyl methacrylate, polyvinyl pyrrolidone, polyacrylamide,polyethylene oxide (PEO), PEO block copolymers, silicone, and the like.

As used herein, the term “surface” refers to material that is near or atan interface between two different phases, chemicals, or states ofmatter. For example, a thin film garnet membrane or separator whenexposed to air has a surface described by the periphery or outsideportion of the membrane or separator which contacts the air. Forrectangular-shaped membranes or separators, there is a top and a bottomsurface which both individually have higher surface areas than each ofthe four side surfaces individually. In this rectangular membrane orseparator example, such as the example shown in FIG. 13, there are alsofour side surfaces which have surface areas less than either or both ofthe top and bottom surfaces. For disc-shaped membranes or separators,such as the example shown in FIG. 14, there is a top and a bottomsurface which both individually have higher surface areas than thecircumference-side of the disc. When used as an electrolyte membrane orseparator in an electrochemical cell, the top or bottom surface is theside or part of the membrane or separator which contacts the negativeelectrode (i.e., Li metal), which contacts the positive electrode (i.e.cathode or catholyte in cathode), and/or which contacts a layer orbonding agent disposed between the membrane or separator and thepositive electrode. A surface has larger x- and y-axis physicaldimensions that it does z-axis physical dimensions, wherein the z-axisis the axis perpendicular to the surface. The depth or thickness of asurface can be of molecular order of magnitude or up to 1 micron. Oxidesurfaces can include dangling bonds, excess hydroxyl groups, bridgingoxides, or a variety of other species which result in the oxide surfacehaving a chemical composition that may be stoichiometrically differentfrom the bulk. For example, in some of the membranes or separators setforth herein, the bulk is characterized by a chemical formula ofLi_(x)La₇Zr₂O₁₂Al₂O₃ and the surface is characterized by a chemicalformula of Li_(y)La₇Zr₂O₁₂Al₂O₃, wherein, in this paragraph, x isgreater than y.

As used herein, the term “bulk,” refers to a portion or part of amaterial that is extended in space in three-dimensions by at least 1micron. The bulk refers to the portion or part of a material which isexclusive of its surface, as defined above.

As used herein, the terms “cathode” and “anode” refer to the electrodesof a battery. During a charge cycle in a Li-secondary battery, Li ionsleave the cathode and move through an electrolyte and to the anode.During a charge cycle, electrons leave the cathode and move through anexternal circuit to the anode. During a discharge cycle in aLi-secondary battery, Li ions migrate towards the cathode through anelectrolyte and from the anode. During a discharge cycle, electronsleave the anode and move through an external circuit to the cathode.

As used herein, a “catholyte” refers to an ion conductor that isintimately mixed with, or that surrounds, or that contacts the positiveelectrode active material. Catholytes suitable with the embodimentsdescribed herein include, but are not limited to, catholytes having thecommon name LPS, LXPS, LXPSO, where X is Si, Ge, Sn, As, Al, LATS, oralso Li-stuffed garnets, or combinations thereof, and the like.Catholytes may also be liquid, gel, semi-liquid, semi-solid, polymer,and/or solid polymer ion conductors known in the art. Catholytes includethose catholytes set forth in US Patent Application Publication No.2015-0171465, which published on Jun. 18, 2015, entitled SOLID STATECATHOLYTE OR ELECTROLYTE FOR BATTERY USING LiAMPBSC (M=Si, Ge, AND/ORSn), filed May 15, 2014, the contents of which are incorporated byreference in their entirety. Catholytes include those catholytes setforth in US Patent Application Publication No. 2015/0099190, publishedon Apr. 9, 2015, entitled GARNET MATERIALS FOR LI SECONDARY BATTERIESAND METHODS OF MAKING AND USING GARNET MATERIALS, and filed Oct. 7,2014, the contents of which are incorporated by reference in theirentirety.

As used herein, the phrase “solid state catholyte,” or the term“catholyte” refers to an ion conductor that is intimately mixed with, orsurrounded by, a cathode (i.e., positive electrode) active material(e.g., a metal fluoride optionally including lithium).

In some examples the catholyte may include a gel electrolyte such as,but not limited to, the electrolyte compositions set forth in U.S. Pat.No. 5,296,318, entitled RECHARGEABLE LITHIUM INTERCALATION BATTERY WITHHYBRID POLYMERIC ELECTROLYTE; also U.S. Pat. No. 5,460,904; also U.S.Pat. No. 5,456,000, to Gozdz, et al., or those compositions set forth inUS Patent Application No. 20020192561, entitled SEPARATORS FORWINDING-TYPE LITHIUM SECONDARY BATTERIES HAVING GEL-TYPE POLYMERELECTROLYTES AND MANUFACTURING METHOD FOR THE SAME, which published Dec.19, 2002.

As used herein, the phrase “current collector” refers to a component orlayer in a secondary battery through which electrons conduct, to or froman electrode in order to complete an external circuit, and which are indirect contact with the electrode to or from which the electronsconduct. In some examples, the current collector is a metal (e.g., Al,Cu, or Ni, steel, alloys thereof, or combinations thereof) layer whichis laminated to a positive or negative electrode. During charging anddischarging, electrons move in the opposite direction to the flow of Liions and pass through the current collector when entering or exiting anelectrode.

As used herein, the term “electrolyte,” refers to a material that allowsions, e.g., Li+, to migrate therethrough but which does not allowelectrons to conduct therethrough. Electrolytes are useful forelectrically isolating the cathode and anodes of a secondary batterywhile allowing ions, e.g., Li⁺, to transmit through the electrolyte.Electrolytes are ionically conductive and electrically insulatingmaterial. Electrolytes are useful for electrically insulating thepositive and negative electrodes of a secondary battery while allowingfor the conduction of ions, e.g., Li⁺, through the electrolyte.

As used herein, the phrase “d₅₀ diameter” or “median diameter (d₅₀)”refers to the median size, in a distribution of sizes, measured bymicroscopy techniques or other particle size analysis techniques, suchas, but not limited to, scanning electron microscopy or dynamic lightscattering. D₅₀ describes a characteristic dimension of particles atwhich 50% of the particles are smaller than the recited size. As usedherein “diameter (d₉₀)” refers to the size, in a distribution of sizes,measured by microscopy techniques or other particle size analysistechniques, including, but not limited to, scanning electron microscopyor dynamic light scattering. D₉₀ includes the characteristic dimensionat which 90% of the particles are smaller than the recited size. As usedherein “diameter (d₁₀)” refers to the size, in a distribution of sizes,measured by microscopy techniques or other particle size analysistechniques, including, but not limited to, scanning electron microscopyor dynamic light scattering. D₁₀ includes the characteristic dimensionat which 10% of the particles are smaller than the recited size.

As used herein, the term “rational number” refers to any number whichcan be expressed as the quotient or fraction (e.g., p/q) of two integers(e.g., p and q), with the denominator (e.g., q) not equal to zero.Example rational numbers include, but are not limited to, 1, 1.1, 1.52,2, 2.5, 3, 3.12, and 7.

As used herein the phrase “free-standing thin film,” refers to a filmthat is not adhered or supported by an underlying substrate. In someexamples, free-standing thin film is a film that is self-supporting,which can be mechanically manipulated or moved without need of substrateadhered or fixed thereto.

As used herein, the molar ratios, unless specified to the contrary,describe the ratio of constituent elements as batched in the reactionused to make the described material.

As used herein, a “thickness” by which is film is characterized refersto the distance, or median measured distance, between the top and bottomfaces of a film. As used herein, the top and bottom faces refer to thesides of the film having the largest surface areas.

As used herein, the phrase “film thickness” refers to the distance, ormedian measured distance, between the top and bottom faces of a film. Asused herein, the top and bottom faces refer to the sides of the filmhaving the largest surface areas.

As used herein the word “thickness” in the phrase “a thin electrolytemembrane, having top and bottom surfaces and a thickness therebetween”refers to the distance, or median measured distance, between the top andbottom surfaces of a film. As used herein, the top and bottom surfacesrefer to the sides of the film having the largest surface areas.

As used herein, electrolyte separator or membrane thickness is measuredby cross-sectional scanning electron microscopy.

As used herein the phrase “active electrode material,” or “activematerial,” refers to a material that is suitable for use as a Lirechargeable battery and which undergoes a chemical reaction during thecharging and discharging cycles. For examples, and “active cathodematerial,” includes a metal fluoride that converts to a metal andlithium fluoride during the discharge cycle of a Li rechargeablebattery.

As used herein the phrase “active anode material” refers to an anodematerial that is suitable for use in a Li rechargeable battery thatincludes an active cathode material as defined above. In some examples,the active material is Lithium metal. In some of the methods set forthherein, the sintering temperatures are high enough to melt the Lithiummetal used as the active anode material.

As used herein the phrase “free-standing thin film,” refers to a filmthat is not adhered or supported by an underlying substrate. In someexamples, free-standing thin film is a film that is self-supporting,which can be mechanically manipulated or moved without need of substrateadhered or fixed thereto.

As used herein, the phrase “density as determined by geometricmeasurements,” refers to measurements of density obtained by physicalmass and volume measurements. Density is determined by the ratio ofmeasured mass to the measured volume. Customary techniques including theArchimedes method have been employed for such determinations.

As used herein, the phrase “current collector” refers to a component orlayer in a secondary battery through which electrons conduct, to or froman electrode in order to complete an external circuit, and which are indirect contact with the electrode to or from which the electronsconduct. In some examples, the current collector is a metal (e.g., Al,Cu, or Ni, steel, alloys thereof, or combinations thereof) layer whichis laminated to a positive or negative electrode. During charging anddischarging, electrons move in the opposite direction to the flow of Liions and pass through the current collector when entering or exiting anelectrode.

As used herein, the phrase “slot casting,” refers to a depositionprocess whereby a substrate is coated, or deposited, with a solution,liquid, slurry, or the like by flowing the solution, liquid, slurry, orthe like, through a slot or mold of fixed dimensions that is placedadjacent to, in contact with, or onto the substrate onto which thedeposition or coating occurs. In some examples, slot casting includes aslot opening of about 1 to 100 μm.

As used herein, the term “laminating” refers to the process ofsequentially depositing a layer of one precursor specie, e.g., a lithiumprecursor specie, onto a deposition substrate and then subsequentlydepositing an additional layer onto an already deposited layer using asecond precursor specie, e.g., a transition metal precursor specie. Thislaminating process can be repeated to build up several layers ofdeposited vapor phases. As used herein, the term “laminating” alsorefers to the process whereby a layer comprising an electrode, e.g.,positive electrode or cathode active material comprising layer, iscontacted to a layer comprising another material, e.g., garnetelectrolyte. The laminating process may include a reaction or use of abinder which adheres of physically maintains the contact between thelayers which are laminated.

As used herein, the phrase “green film” refers to an unsintered filmincluding at least one member selected from garnet materials, precursorsto garnet materials, calcined garnet materials, binder, solvent, carbon,dispersant, or combinations thereof.

As used herein the phrase “providing an unsintered thin film,” refers tothe provision of, generation or, presentation of, or delivery of anunsintered thin film or a green film defined above. For example,providing an unsintered thin film refers to the process of making anunsintered thin film available, or delivering an unsintered thin film,such that the unsintered thin film can be used as set forth in a methoddescribed herein.

As used herein the phrase “unsintered thin film,” refers to a thin film,including the components and materials described herein, but which isnot sintered by a sintering method set forth herein. Thin refers, forexample, to a film that has an average thickness dimensions of about 10nm to about 100 μm. In some examples, thin refers to a film that is lessthan about 1 μm, 10 μm or 50 μm in thickness.

As used herein, the phrase “evaporating the cathode current collector,”refers to a process of providing or delivering a metal, such as, but notlimited to, copper, nickel, aluminum, or an combination thereof, invapor or atomized form such that the metal contacts and forms anadhering layer to the cathode, catholyte, or combinations thereof or tothe anode, anolyte, or combinations thereof. This process results in theformation of a metal layer on a cathode or anode such that the metallayer and the cathode or anode are in electrical communication.

As used herein the term “making,” refers to the process or method offorming or causing to form the object that is made. For example, makingan energy storage electrode includes the process, process steps, ormethod of causing the electrode of an energy storage device to beformed. The end result of the steps constituting the making of theenergy storage electrode is the production of a material that isfunctional as an electrode.

As used herein the phrase “energy storage electrode,” refers to, forexample, an electrode that is suitable for use in an energy storagedevice, e.g., a lithium rechargeable battery or Li-secondary battery. Asused herein, such an electrode is capable of conducting electrons and Liions as necessary for the charging and discharging of a rechargeablebattery.

As used herein, the phrase “electrochemical device” refers to an energystorage device, such as, but not limited to a Li-secondary battery thatoperates or produces electricity or an electrical current by anelectrochemical reaction, e.g., a conversion chemistry reaction such as3Li+FeF₃↔3LiF+Fe.

As used herein, the phrase “providing” refers to the provision of,generation or, presentation of, or delivery of that which is provided.

As used herein, the phrase “lithium stuffed garnet” refers to oxidesthat are characterized by a crystal structure related to a garnetcrystal structure. Lithium-stuffed garnets include compounds having theformula Li_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Ta_(E)O_(F), orLi_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2, 10<F<13, and M′ and M″ are each, independently in eachinstance selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta,or Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein 5<a<7.7; 2<b<4;0<c≤2.5; 0≤d<2; 0≤e<2, 10<f<13 and Me″ is a metal selected from Nb, Ta,V, W, Mo, or Sb and as described herein. Garnets, as used herein, alsoinclude those garnets described above that are doped with Al₂O₃.Garnets, as used herein, also include those garnets described above thatare doped so that Al³⁺ substitutes for Li⁺. As used herein,lithium-stuffed garnets, and garnets, generally, include, but are notlimited to, Li_(7.0)La₃(Zr_(t1)+Nb_(t2)+Ta_(t3))O₁₂+0.35Al₂O₃; wherein(t1+t2+t3=subscript 2) so that the La:(Zr/Nb/Ta) ratio is 3:2. Also,garnet used herein includes, but is not limited to,Li_(x)La₃Zr₂O₁₂+yAl₂O₃, wherein x ranges from 5.5 to 9; and y rangesfrom 0 to 1. In some examples x is 7 and y is 1.0. In some examples x is7 and y is 0.35. In some examples x is 7 and y is 0.7. In some examplesx is 7 and y is 0.4. Also, garnets as used herein include, but are notlimited to, Li_(x)La₃Zr₂O₁₂+yAl₂O₃.

As used herein, garnet does not include YAG-garnets (i.e., yttriumaluminum garnets, or, e.g., Y₃Al₅O₁₂). As used herein, garnet does notinclude silicate-based garnets such as pyrope, almandine, spessartine,grossular, hessonite, or cinnamon-stone, tsavorite, uvarovite andandradite and the solid solutions pyrope-almandine-spessarite anduvarovite-grossular-andradite. Garnets herein do not includenesosilicates having the general formula X₃Y₂(SiO₄)₃ wherein X is Ca,Mg, Fe, and, or, Mn; and Y is Al, Fe, and, or, Cr.

As used herein, the phrase “garnet precursor chemicals” or “chemicalprecursor to a Garnet-type electrolyte” refers to chemicals which reactto form a lithium stuffed garnet material described herein. Thesechemical precursors include, but are not limited to lithium hydroxide(e.g., LiOH), lithium oxide (e.g., Li₂O), lithium carbonate (e.g.,LiCO₃), zirconium oxide (e.g., ZrO₂), lanthanum oxide (e.g., La₂O₃),aluminum oxide (e.g., Al₂O₃), aluminum (e.g., Al), aluminum nitrate(e.g., AlNO₃), aluminum nitrate nonahydrate, niobium oxide (e.g.,Nb₂O₅), tantalum oxide (e.g., Ta₂O₅).

As used herein the phrase “garnet-type electrolyte,” refers to anelectrolyte that includes a garnet or lithium stuffed garnet materialdescribed herein as the ionic conductor.

As used herein, the phrase “doped with alumina” means that Al₂O₃ is usedto replace certain components of another material, e.g., a garnet. Alithium stuffed garnet that is doped with Al₂O₃ refers to garnet whereinaluminum (Al) substitutes for an element in the lithium stuffed garnetchemical formula, which may be, for example, Li or Zr.

As used herein, the phrase “aluminum reaction vessel” refers to acontainer or receptacle into which precursor chemicals are placed inorder to conduct a chemical reaction to produce a product, e.g., alithium stuffed garnet material.

As used herein, the phrase “high conductivity,” refers to aconductivity, such as ionic conductivity, that is greater than 10⁻⁵ S/cmat room temperature. In some examples, high conductivity includes aconductivity greater than 10⁻⁵ S/cm at room temperature.

As used herein, the phrase “Zr is partially replaced by a higher valencespecies” refers to the substitution of Zr⁴⁺ with a species that has, forexample, a 5⁺ or 6⁺ charge. For example, if some Nb⁵⁺ can reside in alattice position in a garnet crystal structure where a Zr atom residesand in doing so substitute for Zr⁴⁺, then Zr is partially replaced byNb. This is also referred to as niobium doping.

As used herein, the phrase “subscripts and molar coefficients in theempirical formulas are based on the quantities of raw materialsinitially batched to make the described examples” means the subscripts,(e.g., 7, 3, 2, 12 in Li₇La₃Zr₂O₁₂ and the coefficient 0.35 in0.35Al₂O₃) refer to the respective elemental ratios in the chemicalprecursors (e.g., LiOH, La₂O₃, ZrO₂, Al₂O₃) used to prepare a givenmaterial, (e.g., Li₇La₃Zr₂O₁₂.0.35Al₂O₃).

As used herein, the term “grains” refers to domains of material withinthe bulk of a material that have a physical boundary which distinguishesthe grain from the rest of the material. For example, in some materialsboth crystalline and amorphous components of a material, often havingthe same chemical composition, are distinguished from each other by theboundary between the crystalline component and the amorphous component.The approximate diameter or maximum dimensions of the boundaries of acrystalline component, or of an amorphous component, is referred hereinas the grain size.

As used herein the phrase “active electrode material,” or “activematerial,” refers to a material that is suitable for use as a Lirechargeable battery and which undergoes a chemical reaction during thecharging and discharging cycles. For examples, and “active cathodematerial,” includes a metal fluoride that converts to a metal andlithium fluoride during the discharge cycle of a Li rechargeablebattery.

As used herein the phrase “active anode material” refers to an anodematerial that is suitable for use in a Li rechargeable battery thatincludes an active cathode material as defined above. In some examples,the active material is Lithium metal. In some of the methods set forthherein, the sintering temperatures are high enough to melt the Lithiummetal used as the active anode material.

As used herein the phrase “conductive additive,” refers to a materialthat is mixed with the cathode active material in order to improve theconductivity of the cathode. Examples includes, but are not limited to,carbon and the various forms of carbon, e.g., ketjen black, VGCF,acetylene black, graphite, graphene, nanotubes, nanofibers, the like,and combinations thereof.

As used herein the phrase “casting a film,” refers to the process ofdelivering or transferring a liquid or a slurry into a mold, or onto asubstrate, such that the liquid or the slurry forms, or is formed into,a film. Casting may be done via doctor blade, meyer rod, comma coater,gravure coater, microgravure, reverse comma coater, slot dye, slipand/or tape casting, and other methods known to those skilled in theart.

As used herein the phrase “applying a pressure,” refers to a processwhereby an external device, e.g., a calender, induces a pressure inanother material.

As used herein the phrase “burning the binder or calcining theunsintered film,” refers to the process whereby a film that includes abinder is heated, optionally in an environment that includes anoxidizing specie, e.g., O₂, in order to burn the binder or induce achemical reaction that drives off, or removes, the binder, e.g.,combustion, or which causes a film having a binder to sinter, to becomemore dense or less porous.

As used herein the phrase “composite electrode,” refers to an electrodethat is composed of more than one material. For example, a compositeelectrode may include, but is not limited to, an active cathode materialand a garnet-type electrolyte in intimate mixture or ordered layers orwherein the active material and the electrolyte are interdigitated.

As used herein the phrase “inert setter plates,” refer to plates, whichare normally flat, and which are unreactive with a material that issintered. Inert setter plates can be metallic or ceramic, and,optionally, these setter plates can be porous to provide for thediffusion of gases and vapors therethrough when a sintered material isactually sintered. Inert setter plates are exemplified in U.S.Provisional Patent Application No. 62/148,337, filed Apr. 16, 2015.

As used herein the phrase “free-standing thin film,” refers to a filmthat is not adhered or supported by an underlying substrate. In someexamples, free-standing thin film is a film that is self-supporting,which can be mechanically manipulated or moved without need of substrateadhered or fixed thereto.

As used herein the phrase “wherein either the top or bottom surface ischaracterized as having substantially no layer thereupon comprising alithium carbonate, lithium hydroxide, lithium oxide, lithium peroxide, ahydrate thereof, an oxide thereof, or a combination thereof,” refers toa material set forth herein where the material's top or bottom surfaceis not observed to have a lithium carbonate, lithium hydroxide, lithiumoxide, lithium peroxide, a hydrate thereof, an oxide thereof, or acombination thereof when analyzed by Raman, FT-IR, or XPS spectroscopy.

i. Electrolytes

In some examples, set forth herein is a thin electrolyte separator,having top and bottom surfaces and a thickness therebetween, wherein thetop or bottom surface length or width is greater than the thickness by afactor of ten (10) or more, and the thickness is from about 10 nm toabout 100 μm. In some examples, the electrolyte bulk is characterized bythe chemical formula Li_(x)La₃Zr₂O₁₂ y(Al₂O₃), wherein 3≤x≤8 and 0≤y≤1.In some examples, the top or bottom surface is characterized as having alayer thereupon, greater than 1 nm and less than 1 μm, comprising alithium carbonate, lithium hydroxide, lithium oxide, lithium peroxide, ahydrate thereof, an oxide thereof, or a combination thereof.

In some examples, set forth herein is a thin electrolyte separator,having top and bottom surfaces and a thickness therebetween, wherein thetop or bottom surface length or width is greater than the thickness by afactor of ten (10) or more, and the thickness is from about 10 nm toabout 100 μm. In some examples, the electrolyte bulk is characterized bythe chemical formula LixLa3Zr2O12 y(Al2O3), wherein 3≤x≤8 and 0≤y≤1. Incertain examples, either the top or bottom surface is characterized ashaving substantially no layer thereupon comprising a lithium carbonate,lithium hydroxide, lithium oxide, lithium peroxide, a hydrate thereof,an oxide thereof, or a combination thereof. In certain examples, eitherthe top or bottom surface is characterized as having substantially nolayer thereupon comprising a lithium carbonate. In certain examples,either the top or bottom surface is characterized as havingsubstantially no layer thereupon comprising a lithium hydroxide. Incertain examples, either the top or bottom surface is characterized ashaving substantially no layer thereupon comprising a lithium oxide. Incertain examples, either the top or bottom surface is characterized ashaving substantially no layer thereupon comprising a lithium peroxide.In certain examples, either the top or bottom surface is characterizedas having substantially no layer thereupon comprising a hydrate of anyof the aforementioned. In certain examples, either the top or bottomsurface is characterized as having substantially no layer thereuponcomprising a peroxide of any of the aforementioned. In certain examples,either the top or bottom surface is characterized as havingsubstantially no layer thereupon comprising an oxide of any of theaforementioned.

In some examples, the electrolyte separator has a top or bottom surfacelength or width is from about 100 μm to 100 cm.

In some examples, the electrolyte separator has an x as 3, 3.5, 4, 4.5,5, 5.5, 6, 6.5, 7, 7.5, or 8.

In some examples, the electrolyte separator bulk is characterized by thechemical formula Li₃La₃Zr₂O_(h)0.2(Al₂O₃), Li₃La₃Zr₂O_(h)0.25(Al₂O₃),Li₃La₃Zr₂O_(h)0.3(Al₂O₃), Li₃La₃Zr₂O_(h)0.35(Al₂O₃),Li₃La₃Zr₂O_(h)0.4(Al₂O₃), Li₃La₃Zr₂O_(h)0.45(Al₂O₃),Li₃La₃Zr₂O_(h)0.5(Al₂O₃), Li₃La₃Zr₂O_(h)0.55(Al₂O₃),Li₃La₃Zr₂O_(h)0.6(Al₂O₃), Li₃La₃Zr₂O_(h)0.65(Al₂O₃),Li₃La₃Zr₂O_(h)0.7(Al₂O₃), Li₃La₃Zr₂O_(h)0.75(Al₂O₃),Li₃La₃Zr₂O_(h)0.8(Al₂O₃), Li₃La₃Zr₂O_(h)0.85(Al₂O₃),Li₃La₃Zr₂O_(h)0.9(Al₂O₃), Li₃La₃Zr₂O_(h)0.95(Al₂O₃),Li₃La₃Zr₂O_(h)(Al₂O₃), Li₅La₃Zr₂O_(h)0.2(Al₂O₃), Li₅La₃Zr₂O_(h)0.25(Al₂O₃), Li₅La₃Zr₂O_(h)0.3(Al₂O₃), Li₅La₃Zr₂O_(h)0.35(Al₂O₃),Li₅La₃Zr₂O_(h)0.4(Al₂O₃), Li₅La₃Zr₂O_(h)0.45(Al₂O₃),Li₅La₃Zr₂O_(h)0.5(Al₂O₃), Li₅La₃Zr₂O_(h)0.55(Al₂O₃),Li₅La₃Zr₂O_(h)0.6(Al₂O₃), Li₅La₃Zr₂O_(h)0.55(Al₂O₃),Li₅La₃Zr₂O_(h)0.7(Al₂O₃), Li₅La₃Zr₂O_(h)0.75(Al₂O₃),Li₅La₃Zr₂O_(h)0.8(Al₂O₃), Li₅La₃Zr₂O_(h)0.85(Al₂O₃),Li₅La₃Zr₂O_(h)0.9(Al₂O₃), Li₅La₃Zr₂O_(h)0.95(Al₂O₃),Li₅La₃Zr₂O_(h)(Al₂O₃), Li₆La₃Zr₂O_(h)0.2(Al₂O₃), Li₆La₃Zr₂O_(h)0.25(Al₂O₃), Li₆La₃Zr₂O_(h)0.3(Al₂O₃), Li₆La₃Zr₂O_(h)0.35(Al₂O₃),Li₆La₃Zr₂O_(h)0.4(Al₂O₃), Li₃La₃Zr₂O_(h)0.45(Al₂O₃),Li₆La₃Zr₂O_(h)0.5(Al₂O₃), Li₆La₃Zr₂O_(h)0.55(Al₂O₃),Li₆La₃Zr₂O_(h)0.6(Al₂O₃), Li₆La₃Zr₂O_(h)0.55(Al₂O₃),Li₆La₃Zr₂O_(h)0.7(Al₂O₃), Li₆La₃Zr₂O_(h)0.75(Al₂O₃),Li₆La₃Zr₂O_(h)0.8(Al₂O₃), Li₆La₃Zr₂O_(h)0.85(Al₂O₃),Li₆La₃Zr₂O_(h)0.9(Al₂O₃), Li₆La₃Zr₂O_(h)0.95(Al₂O₃),Li₆La₃Zr₂O_(h)(Al₂O₃), Li₇La₃Zr₂O_(h)0.2(Al₂O₃),Li₇La₃Zr₂O_(h)0.25(Al₂O₃), Li₇La₃Zr₂O_(h)0.3(Al₂O₃),Li₇La₃Zr₂O_(h)0.35(Al₂O₃), Li₇La₃Zr₂O_(h)0.4(Al₂O₃),Li₇La₃Zr₂O_(h)0.45(Al₂O₃), Li₇La₃Zr₂O_(h)0.5(Al₂O₃),Li₇La₃Zr₂O_(h)0.55(Al₂O₃), Li₇La₃Zr₂O_(h)0.6(Al₂O₃),Li₇La₃Zr₂O_(h)0.65(Al₂O₃), Li₇La₃Zr₂O_(h)0.7(Al₂O₃),Li₇La₃Zr₂O_(h)0.75(Al₂O₃), Li₇La₃Zr₂O_(h)0.8(Al₂O₃),Li₇La₃Zr₂O_(h)0.85(Al₂O₃), Li₇La₃Zr₂O_(h) 0.9(Al₂O₃),Li₇La₃Zr₂O_(h)0.95(Al₂O₃), or Li₇La₃Zr₂O_(h)(Al₂O₃),Li₇La₃Zr₂O_(h)0.3(Al₂O₃), Li₇La₃Zr₂O_(h)0.35(Al₂O₃),Li₇La₃Zr₂O_(h)0.4(Al₂O₃), Li₇La₃Zr₂O_(h)0.45(Al₂O₃),Li₇La₃Zr₂O_(h)0.5(Al₂O₃), Li₇La₃Zr₂O_(h)0.55(Al₂O₃),Li₇La₃Zr₂O_(h)0.6(Al₂O₃), Li₇La₃Zr₂O_(h)0.65(Al₂O₃),Li₇La₃Zr₂O_(h)0.7(Al₂O₃), Li₇La₃Zr₂O_(h)0.75(Al₂O₃),Li₇La₃Zr₂O_(h)0.8(Al₂O₃), Li₇La₃Zr₂O_(h)0.85(Al₂O₃),Li₇La₃Zr₂O_(h)0.9(Al₂O₃), Li₇La₃Zr₂O_(h)0.95(Al₂O₃),Li₇La₃Zr₂O_(h)(Al₂O₃), Li₈La₃Zr₂O_(h)0.2(Al₂O₃),Li₈La₃Zr₂O_(h)0.25(Al₂O₃), Li₈La₃Zr₂O_(h)0.3(Al₂O₃),Li₈La₃Zr₂O_(h)0.35(Al₂O₃), Li₈La₃Zr₂O_(h)0.4(Al₂O₃),Li₈La₃Zr₂O_(h)0.45(Al₂O₃), Li₈La₃Zr₂O_(h)0.5(Al₂O₃),Li₈La₃Zr₂O_(h)0.55(Al₂O₃), Li₈La₃Zr₂O_(h)0.6(Al₂O₃),Li₈La₃Zr₂O_(h)0.65(Al₂O₃), Li₈La₃Zr₂O_(h)0.8(Al₂O₃),Li₈La₃Zr₂O_(h)0.85(Al₂O₃), Li₈La₃Zr₂O_(h)0.8(Al₂O₃),Li₈La₃Zr₂O_(h)0.85(Al₂O₃), Li₈La₃Zr₂O_(h)0.9(Al₂O₃),Li₈La₃Zr₂O_(h)0.95(Al₂O₃), or Li₈La₃Zr₂O_(h)(Al₂O₃),Li₈La₃Zr₂O_(h)0.3(Al₂O₃), Li₈La₃Zr₂O_(h)0.35(Al₂O₃),Li₈La₃Zr₂O_(h)0.4(Al₂O₃), Li₈La₃Zr₂O_(h)0.45(Al₂O₃),Li₈La₃Zr₂O_(h)0.5(Al₂O₃), Li₈La₃Zr₂O_(h)0.55(Al₂O₃),Li₈La₃Zr₂O_(h)0.6(Al₂O₃), Li₈La₃Zr₂O_(h)0.65(Al₂O₃),Li₈La₃Zr₂O_(h)0.8(Al₂O₃), Li₈La₃Zr₂O_(h)0.85(Al₂O₃),Li₈La₃Zr₂O_(h)0.8(Al₂O₃), Li₈La₃Zr₂O_(h)0.85(Al₂O₃),Li₈La₃Zr₂O_(h)0.9(Al₂O₃), Li₈La₃Zr₂O_(h)0.95(Al₂O₃), orLi₈La₃Zr₂O_(h)(Al₂O₃). In these examples, subscript h is a numberselected so that the chemical characterized by the formula is chargeneutral. Subscript h can be any rational number greater than 0 or lessthan 15 as required to maintain charge neutrality. In some examples, his0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8,8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, or 15. Incertain examples, h is 9, 10, 11, 12, or 13. In some examples, h is 10,11, or 12. In other examples, h is 11 or 12. In other examples, his 12or 13. In certain examples, his 12.

In some examples, the electrolyte separator bulk is characterized by thechemical formula Li₃La₃Zr₂O₁₂0.2(Al₂O₃), Li₃La₃Zr₂O₁₂0.25(Al₂O₃),Li₃La₃Zr₂O₁₂0.3(Al₂O₃), Li₃La₃Zr₂O₁₂0.35(Al₂O₃), Li₃La₃Zr₂O₁₂0.4(Al₂O₃),Li₃La₃Zr₂O₁₂0.45(Al₂O₃), Li₃La₃Zr₂O₁₂0.5(Al₂O₃),Li₃La₃Zr₂O₁₂0.55(Al₂O₃), Li₃La₃Zr₂O₁₂0.6(Al₂O₃),Li₃La₃Zr₂O₁₂0.65(Al₂O₃), Li₃La₃Zr₂O₁₂0.7(Al₂O₃),Li₃La₃Zr₂O₁₂0.75(Al₂O₃), Li₃La₃Zr₂O₁₂0.8(Al₂O₃),Li₃La₃Zr₂O₁₂0.85(Al₂O₃), Li₃La₃Zr₂O₁₂0.9(Al₂O₃),Li₃La₃Zr₂O₁₂0.95(Al₂O₃), Li₃La₃Zr₂O₁₂(Al₂O₃), Li₅La₃Zr₂O₁₂0.2(Al₂O₃),Li₅La₃Zr₂O₁₂ 0.25(Al₂O₃), Li₅La₃Zr₂O₁₂0.3(Al₂O₃),Li₅La₃Zr₂O₁₂0.35(Al₂O₃), Li₅La₃Zr₂O₁₂0.4(Al₂O₃),Li₅La₃Zr₂O₁₂0.45(Al₂O₃), Li₅La₃Zr₂O₁₂0.5(Al₂O₃),Li₅La₃Zr₂O₁₂0.55(Al₂O₃), Li₅La₃Zr₂O₁₂0.6(Al₂O₃),Li₅La₃Zr₂O₁₂0.55(Al₂O₃), Li₅La₃Zr₂O₁₂0.7(Al₂O₃),Li₅La₃Zr₂O₁₂0.75(Al₂O₃), Li₅La₃Zr₂O₁₂0.8(Al₂O₃),Li₅La₃Zr₂O₁₂0.85(Al₂O₃), Li₅La₃Zr₂O₁₂ 0.9(Al₂O₃),Li₅La₃Zr₂O₁₂0.95(Al₂O₃), Li₅La₃Zr₂O₁₂(Al₂O₃), Li₆La₃Zr₂O₁₂0.2(Al₂O₃),Li₆La₃Zr₂O₁₂ 0.25(Al₂O₃), Li₆La₃Zr₂O₁₂0.3(Al₂O₃),Li₆La₃Zr₂O₁₂0.35(Al₂O₃), Li₆La₃Zr₂O₁₂0.4(Al₂O₃),Li₃La₃Zr₂O₁₂0.45(Al₂O₃), Li₆La₃Zr₂O₁₂0.5(Al₂O₃),Li₆La₃Zr₂O₁₂0.55(Al₂O₃), Li₆La₃Zr₂O₁₂0.6(Al₂O₃),Li₆La₃Zr₂O₁₂0.55(Al₂O₃), Li₆La₃Zr₂O₁₂0.7(Al₂O₃),Li₆La₃Zr₂O₁₂0.75(Al₂O₃), Li₆La₃Zr₂O₁₂0.8(Al₂O₃),Li₆La₃Zr₂O₁₂0.85(Al₂O₃), Li₆La₃Zr₂O₁₂0.9(Al₂O₃),Li₆La₃Zr₂O₁₂0.95(Al₂O₃), Li₆La₃Zr₂O₁₂(Al₂O₃), Li₇La₃Zr₂O₁₂0.2(Al₂O₃),Li₇La₃Zr₂O₁₂0.25(Al₂O₃), Li₇La₃Zr₂O₁₂0.3(Al₂O₃),Li₇La₃Zr₂O₁₂0.35(Al₂O₃), Li₇La₃Zr₂O₁₂0.4(Al₂O₃),Li₇La₃Zr₂O₁₂0.45(Al₂O₃), Li₇La₃Zr₂O₁₂0.5(Al₂O₃),Li₇La₃Zr₂O₁₂0.55(Al₂O₃), Li₇La₃Zr₂O₁₂0.6(Al₂O₃),Li₇La₃Zr₂O₁₂0.65(Al₂O₃), Li₇La₃Zr₂O₁₂0.7(Al₂O₃),Li₇La₃Zr₂O₁₂0.75(Al₂O₃), Li₇La₃Zr₂O₁₂0.8(Al₂O₃),Li₇La₃Zr₂O₁₂0.85(Al₂O₃), Li₇La₃Zr₂O₁₂ 0.9(Al₂O₃),Li₇La₃Zr₂O₁₂0.95(Al₂O₃), or Li₇La₃Zr₂O₁₂(Al₂O₃), Li₇La₃Zr₂O₁₂0.3(Al₂O₃),Li₇La₃Zr₂O₁₂0.35(Al₂O₃), Li₇La₃Zr₂O₁₂0.4(Al₂O₃),Li₇La₃Zr₂O₁₂0.45(Al₂O₃), Li₇La₃Zr₂O₁₂0.5(Al₂O₃),Li₇La₃Zr₂O₁₂0.55(Al₂O₃), Li₇La₃Zr₂O₁₂0.6(Al₂O₃),Li₇La₃Zr₂O₁₂0.65(Al₂O₃), Li₇La₃Zr₂O₁₂0.7(Al₂O₃),Li₇La₃Zr₂O₁₂0.75(Al₂O₃), Li₇La₃Zr₂O₁₂0.8(Al₂O₃),Li₇La₃Zr₂O₁₂0.85(Al₂O₃), Li₇La₃Zr₂O₁₂0.9(Al₂O₃),Li₇La₃Zr₂O₁₂0.95(Al₂O₃), Li₇La₃Zr₂O₁₂(Al₂O₃), Li₈La₃Zr₂O₁₂0.2(Al₂O₃),Li₈La₃Zr₂O₁₂0.25(Al₂O₃), Li₈La₃Zr₂O₁₂0.3(Al₂O₃),Li₈La₃Zr₂O₁₂0.35(Al₂O₃), Li₈La₃Zr₂O₁₂0.4(Al₂O₃),Li₈La₃Zr₂O₁₂0.45(Al₂O₃), Li₈La₃Zr₂O₁₂0.5(Al₂O₃),Li₈La₃Zr₂O₁₂0.55(Al₂O₃), Li₈La₃Zr₂O₁₂0.6(Al₂O₃),Li₈La₃Zr₂O₁₂0.65(Al₂O₃), Li₈La₃Zr₂O₁₂0.8(Al₂O₃),Li₈La₃Zr₂O₁₂0.85(Al₂O₃), Li₈La₃Zr₂O₁₂0.8(Al₂O₃),Li₈La₃Zr₂O₁₂0.85(Al₂O₃), Li₈La₃Zr₂O₁₂0.9(Al₂O₃),Li₈La₃Zr₂O₁₂0.95(Al₂O₃), or Li₈La₃Zr₂O₁₂(Al₂O₃), Li₈La₃Zr₂O₁₂0.3(Al₂O₃),Li₈La₃Zr₂O₁₂0.35(Al₂O₃), Li₈La₃Zr₂O₁₂0.4(Al₂O₃),Li₈La₃Zr₂O₁₂0.45(Al₂O₃), Li₈La₃Zr₂O₁₂0.5(Al₂O₃),Li₈La₃Zr₂O₁₂0.55(Al₂O₃), Li₈La₃Zr₂O₁₂0.6(Al₂O₃),Li₈La₃Zr₂O₁₂0.65(Al₂O₃), Li₈La₃Zr₂O₁₂0.8(Al₂O₃),Li₈La₃Zr₂O₁₂0.85(Al₂O₃), Li₈La₃Zr₂O₁₂0.8(Al₂O₃),Li₈La₃Zr₂O₁₂0.85(Al₂O₃), Li₈La₃Zr₂O₁₂0.9(Al₂O₃),Li₈La₃Zr₂O₁₂0.95(Al₂O₃), or Li₈La₃Zr₂O₁₂(Al₂O₃).

In some examples, the electrolyte separator electrolyte bulk ischaracterized by a chemical formula different from the top or bottomsurface of the electrolyte separator. In some examples, the electrolyteseparator electrolyte bulk is characterized by the chemical formulaLi_(x1)La₃Zr₂O₁₂ y(Al₂O₃), wherein 3≤x1≤8 and 0≤y≤1;

wherein the top or bottom surface or both is/are characterized by thechemical formula Li_(x2)La₃Zr₂O₁₂ y(Al₂O₃), wherein 3≤x1≤8 and 0≤y≤1,wherein x2 is less than x1.

In some examples, the electrolyte separator has either the top or bottomsurface as characterized as having less than a 0.5 μm thick layerthereupon comprising a lithium carbonate, lithium hydroxide, lithiumoxide, lithium peroxide, a hydrate thereof, an oxide thereof, or acombination thereof. In some examples, either the top or bottom surfaceis characterized as having less than a 0.35 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof. In other example, either the top or bottom surface ischaracterized as having less than a 0.25 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof. In certain examples, either the top or bottom surface ischaracterized as having less than a 0.15 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof. In some of these examples, either the top or bottom surface ischaracterized as having less than a 0.1 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof. In some examples, either the top or bottom surface ischaracterized as having less than a 0.05 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof. In some examples, both the top and bottom surfaces arecharacterized as having a similar thickness layer thereupon comprising alithium carbonate, lithium hydroxide, lithium oxide, lithium peroxide, ahydrate thereof, an oxide thereof, or a combination thereof. In someexamples, both the top and bottom surfaces are characterized as havingno detectable presence of lithium carbonate, lithium hydroxide, lithiumoxide, lithium peroxide, or a combination thereof as detected by XPS orFT-IR. In some examples, both the top and bottom surfaces arecharacterized as having no secondary phases present on the top or bottomsurface, wherein secondary phases are selected from LiAlO₂, Li₂ZrO₃,LaAlO₃, Li₅AlO₄, Li₆Zr₂O₇, La₂(Li_(x)Al_(1-x))O₄, wherein x is from 0 to1, or combinations thereof. In some examples, both the top and bottomsurfaces are characterized as having the same thickness layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof.

In some examples herein, the separator a Li-metal interface areaspecific resistance between 0 and 15 Ωcm² at 60° C. In some examples,the Li-metal interface area specific resistance is less than 2 Ωcm² at60° C. In other examples, the Li-metal interface area specificresistance is less than 2 Ωcm² at 25° C. In certain examples, theLi-metal interface area specific resistance is less than 20 Ωcm² at −25°C.

In some examples, the separator is a pellet, a film, free-standing film,or a monolith.

In some examples herein, the lithium carbonate is characterized byLi_(x)(CO₃)_(y) and x is from 0 to 2, and y is from 0 to 1.

In some examples herein, the lithium hydroxide is characterized byLi_(x)(OH)_(y) and x and y are each, independently, from 0 to 1.

In some examples herein, the lithium oxide is characterized byLi_(x)O_(y) and x and y are each, independently, from 0 to 2.

In some examples herein, the electrolyte separator is characterized byan EPR spectrum substantially as shown in FIG. 4.

In some examples herein, the top or bottom surface of the electrolytemembrane or separator is characterized by an FT-IR spectrumsubstantially as shown in FIG. 9

In some of these examples, the top or bottom surface is characterized bya Raman spectrum substantially as shown in FIG. 10.

In some examples herein, set forth are electrolyte separators ormembranes characterized by the chemical formula Li_(x)La₃Zr₂O₁₂+yAl₂O₃,wherein 3≤x≤8 and 0≤y≤1 and having a top or bottom surface that has lessthan 5 atomic % of an amorphous material comprising carbon and oxygen.In some of these examples, the top or bottom surface is in directcontact with Li-metal.

In some examples, the top or bottom surface that has a carbonconcentration at the surface of less than 5 atomic %.

In some examples, the top or bottom surface that has a hydrogenconcentration at the surface of less than 5 atomic %.

In certain examples, the atomic % of carbon is measured by XPS.

In other examples, the atomic % of hydrogen is measured by SIMS.

In some examples herein, the electrolyte separator or membrane has anOxygen (O) vacancy concentration characterized by an EPR signal spindensity of 1×10⁻¹⁸/cm³ to 1×10⁻²⁰/cm³.

In some examples herein, the electrolyte separator or membrane has aspin density equal to about 1×10⁻¹⁹/cm³.

In certain examples, the compositions and methods set forth hereininclude a Garnet-type electrolyte material selected fromLi_(x)La₃Zr₂O_(z).yAl₂O₃, wherein x is from 5 to 7.5; z is from 11 to12.25; and y is from 0 to 1.

, Li_(A)La_(B)M′_(C)M″_(D)M_(E)O_(F),Li_(A)La_(u)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2, 10<F<14, and M′ and M′ are each, independently in eachinstance selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta,or Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein 5<a<7.7; 2<b<4;0<c≤2.5; 0≤d<2; 0≤e<2, 10<f<14 and Me″ is a metal selected from Nb, Ta,V, W, Mo, or Sb, or combinations thereof.

In certain examples, the methods set forth herein include a Garnet-typeelectrolyte material selected from Li_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M′_(D)Ta_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2, 10<F<14, and M′ and M″ are each, independently in eachinstance selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta,or Li_(a)La_(b)Zr_(c)Al_(d)Me“_(e)O_(f), wherein 5<a<7.7; 2<b<4;0<c≤2.5; 0≤d<2; 0≤e<2, 10<f<14 and Me” is a metal selected from Nb, Ta,V, W, Mo, or Sb, or combinations thereof.

In certain examples, the methods set forth herein include a Garnet-typeelectrolyte material selected from Li_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Ta_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2, 10<F<13, and M′ and M″ are each, independently in eachinstance selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta,or Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein 5<a<7.7; 2<b<4;0<c≤2.5; 0≤d<2; 0≤e<2, 10<f<13 and Me″ is a metal selected from Nb, Ta,V, W, Mo, or Sb, or combinations thereof.

In certain examples, the methods set forth herein include a Garnet-typeelectrolyte selected from Li_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein4<A<8.5, 1.5<B<4, 0≤C≤2, 0≤D≤2; 0≤E<2, 10<F<14, and M′ and M″ are each,independently in each instance selected from Al, Mo, W, Nb, Sb, Ca, Ba,Sr, Ce, Hf, Rb, or Ta, or combinations thereof.

In certain examples, the methods set forth herein include a Garnet-typeelectrolyte selected from Li_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein4<A<8.5, 1.5<B<4, 0≤C≤2, 0≤D≤2; 0≤E<2, 10<F<13, and M′ and M″ are each,independently in each instance selected from Al, Mo, W, Nb, Sb, Ca, Ba,Sr, Ce, Hf, Rb, or Ta.

In certain examples, the methods set forth herein include a Garnet-typeelectrolyte selected from Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein5<a<7.7; 2<b<4; 0<c≤2.5; 0≤d<2; 0≤e<2, 10<f<14 and Me″ is a metalselected from Nb, Ta, V, W, Mo, or Sb.

In certain examples, the methods set forth herein include a Garnet-typeelectrolyte selected from Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein5<a<7.7; 2<b<4; 0<c≤2.5; 0≤d<2; 0≤e<2, 10<f<13 and Me″ is a metalselected from Nb, Ta, V, W, Mo, or Sb.

In some embodiments, the garnet material described herein is used as anelectrolyte. In some of these embodiments, the garnet has the formulaLi_(x)La₃Zr₂O₁₂.y½Al₂O₃; wherein 5.0<x<9 and 0.1<y<1.5. In some of theseexamples, the electrolyte is Li_(x)La₃Zr₂O₁₂.0.35Al₂O₃. In other ofthese examples, the electrolyte is Li₇La₃Zr₂O₁₂.0.35Al₂O₃.

In some of the examples wherein the garnet is an electrolyte, the garnetdoes not include any Nb, Ta, W or Mo, which is used herein to mean thatthe concentration of those elements (e.g., Nb, Ta, W, or Mo) is 10 partsper million (ppm) or lower. In some examples, the concentration of thoseelements (e.g., Nb, Ta, W, or Mo) is 1 parts per million (ppm) or lower.In some examples, the concentration of those elements (e.g., Nb, Ta, W,or Mo) is 0.1 parts per million (ppm) or lower.

In some examples, the Lithium stuffed garnet set forth herein can berepresented by the general formula Li_(x)A₃B₂O₁₂, wherein 5<x<7. In someof these examples, A is a large ion occupying an 8-fold coordinatedlattice site. In some of these examples, A is La, Sr, Ba, Ca, or acombination thereof. In some examples, B is a smaller more highlycharged ion occupying an octahedral site. In some of these examples, Bis Zr, Hf, Nb, Ta, Sb, V, or a combination thereof. In certain of theseexamples, the composition is doped with 0.3 to 1 molar amount of Al perLi_(x)A₃B₂O₁₂. In certain of these examples, the composition is dopedwith 0.35 molar amount of Al per Li_(x)A₃B₂O₁₂.

In some examples, the lithium stuffed garnet is Li₇La₃Zr₂O₁₂ (LLZ) andis doped with alumina. In certain examples, the LLZ is doped by addingAl₂O₃ to the reactant precursor mix that is used to make the LLZ. Incertain other examples, the LLZ is doped by the aluminum in an aluminumreaction vessel that contacts the LLZ.

In some examples, the alumina doped LLZ has a high conductivity, e.g.,greater than 10⁻⁴ S/cm at room temperature.

In some examples, a higher conductivity is observed when some of the Zris partially replaced by a higher valence species, e.g., Nb, Ta, Sb, orcombinations thereof. In some examples, the conductivity reaches as highas 10⁻³ S/cm at room temperature.

In some examples, the composition set forth herein is Li_(x)A₃B₂O₁₂doped with 0.35 molar amount of Al per Li_(x)A₃B₂O₁₂. In certain ofthese examples, x is 5. In certain other examples, x is 5.5. In yetother examples, x is 6.0. In some other examples, x is 6.5. In stillother examples, x is 7.0. In some other examples, x is 7.5.

In some examples, the garnet-based composition is doped with 0.3, 0.35,0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1molar amount of Al per Li_(x)A₃B₂O₁₂.

In some examples, the garnet-based composition is doped with 0.35 molaramount of Al per Li_(x)A₃B₂O₁₂.

In the examples, herein, the subscripts and molar coefficients in theempirical formulas are based on the quantities of raw materialsinitially batched to make the described examples.

In some examples, the instant disclosure provides a compositionincluding a lithium stuffed garnet and Al₂O₃. In certain examples, thelithium stuffed garnet is doped with alumina. In some examples, thelithium-stuffed garnet is characterized by the empirical formulaLi_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E≤2, 10<F≤13, and M′ and M″ are, independently in eachinstance, either absent or are each independently selected from Al, Mo,W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta; and wherein the molar ratio ofGarnet:Al₂O₃ is between 0.05 and 0.7.

In some examples, the instant disclosure provides a compositionincluding a lithium stuffed garnet and Al₂O₃. In certain examples, thelithium stuffed garnet is doped with alumina. In some examples, thelithium-stuffed garnet is characterized by the empirical formulaLi_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E≤2, 10<F≤13, and M′ and M″ are, independently in eachinstance, either absent or are each independently selected from Al, Mo,W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta; and wherein the molar ratio ofLi:Al is between 0.05 and 0.7.

In some examples, the instant disclosure provides a compositionincluding a lithium stuffed garnet and Al₂O₃. In certain examples, thelithium stuffed garnet is doped with alumina. In some examples, thelithium-stuffed garnet is characterized by the empirical formulaLi_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F), wherein 2<A<10, 2<B<6, 0≤C≤2,0≤D≤2; 0≤E≤3, 8<F≤14, and M′ and M″ are, independently in each instance,either absent or are each independently selected from Al, Mo, W, Nb, Sb,Ca, Ba, Sr, Ce, Hf, Rb, or Ta; and wherein the molar ratio ofGarnet:Al₂O₃ is between 0.01 and 2.

In some examples, the instant disclosure provides a compositionincluding a lithium stuffed garnet and Al₂O₃. In certain examples, thelithium stuffed garnet is doped with alumina. In some examples, thelithium-stuffed garnet is characterized by the empirical formulaLi_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F), wherein 2<A<10, 2<B<6, 0≤C≤2,0≤D≤2; 0≤E≤3, 8<F≤14, and M′ and M″ are, independently in each instance,either absent or are each independently selected from Al, Mo, W, Nb, Sb,Ca, Ba, Sr, Ce, Hf, Rb, or Ta; and wherein the molar ratio of Li:Al isbetween 0.01 and 2.

In some examples, the lithium stuffed garnet isLi_(A)La_(B)Zr_(C)M′_(D)M″_(E)O₁₂ and 5<A<7.7, 2<B<4, 0<C<2.5, M′comprises a metal dopant selected from a material including Al and0<D<2, M″ comprises a metal dopant selected from a material includingNb, Ta, V, W, Mo, Sb, and wherein 0<e<2. In some examples, the lithiumstuffed garnet is a lithium stuffed garnet set forth in U.S. ProvisionalPatent Application No. 61/887,451, entitled METHOD AND SYSTEM FORFORMING GARNET MATERIALS WITH SINTERING PROCESS, filed Oct. 7, 2013, theentire contents of which are herein incorporated by reference in itsentirety for all purposes.

In some of the examples above, A is 6. In some other examples, A is 6.5.In other examples, A is 7.0. In certain other examples, A is 7.5. In yetother examples, A is 8.0.

In some of the examples above, B is 2. In some other examples, B is 2.5.In other examples, B is 3.0. In certain other examples, B is 3.5. In yetother examples, B is 3.5. In yet other examples, B is 4.0.

In some of the examples above, C is 0.5. In other examples C is 0.6. Insome other examples, C is 0.7. In some other examples C is 0.8. Incertain other examples C is 0.9. In other examples C is 1.0. In yetother examples, C is 1.1. In certain examples, C is 1.2. In otherexamples C is 1.3. In some other examples, C is 1.4. In some otherexamples C is 1.5. In certain other examples C is 1.6. In other examplesC is 1.7. In yet other examples, C is 1.8. In certain examples, C is1.9. In yet other examples, C is 2.0. In other examples C is 2.1. Insome other examples, C is 2.2. In some other examples C is 2.3. Incertain other examples C is 2.4. In other examples C is 2.5. In yetother examples, C is 2.6. In certain examples, C is 2.7. In yet otherexamples, C is 2.8. In other examples C is 2.9. In some other examples,C is 3.0.

In some of the examples above, D is 0.5. In other examples D is 0.6. Insome other examples, D is 0.7. In some other examples D is 0.8. Incertain other examples D is 0.9. In other examples D is 1.0. In yetother examples, D is 1.1. In certain examples, D is 1.2. In otherexamples D is 1.3. In some other examples, D is 1.4. In some otherexamples D is 1.5. In certain other examples D is 1.6. In other examplesD is 1.7. In yet other examples, D is 1.8. In certain examples, D is1.9. In yet other examples, D is 2.0. In other examples D is 2.1. Insome other examples, D is 2.2. In some other examples D is 2.3. Incertain other examples D is 2.4. In other examples D is 2.5. In yetother examples, D is 2.6. In certain examples, D is 2.7. In yet otherexamples, D is 2.8. In other examples D is 2.9. In some other examples,D is 3.0.

In some of the examples above, E is 0.5. In other examples E is 0.6. Insome other examples, E is 0.7. In some other examples E is 0.8. Incertain other examples E is 0.9. In other examples E is 1.0. In yetother examples, E is 1.1. In certain examples, E is 1.2. In otherexamples E is 1.3. In some other examples, E is 1.4. In some otherexamples E is 1.5. In certain other examples E is 1.6. In other examplesE is 1.7. In yet other examples, E is 1.8. In certain examples, E is1.9. In yet other examples, E is 2.0. In other examples E is 2.1. Insome other examples, E is 2.2. In some other examples E is 2.3. Incertain other examples E is 2.4. In other examples E is 2.5. In yetother examples, E is 2.6. In certain examples, E is 2.7. In yet otherexamples, E is 2.8. In other examples E is 2.9. In some other examples,E is 3.0.

In some of the examples above, F is 11.1. In other examples F is 11.2.In some other examples, F is 11.3. In some other examples F is 11.4. Incertain other examples F is 11.5. In other examples F is 11.6. In yetother examples, F is 11.7. In certain examples, F is 11.8. In otherexamples F is 11.9. In some other examples, F is 12. In some otherexamples F is 12.1. In certain other examples F is 12.2. In otherexamples F is 12.3. In yet other examples, F is 12.3. In certainexamples, F is 12.4. In yet other examples, F is 12.5. In other examplesF is 12.6. In some other examples, F is 12.7. In some other examples Fis 12.8. In certain other examples E is 12.9. In other examples F is 13.

In some particular examples, provided herein is a compositioncharacterized by the empirical formula Li_(x)La₃Zr₂O₁₂.y½Al₂O₃; wherein5.0<x<9 and 0.1<y<1.5. In some examples, x is 5. In other examples, x is5.5. In some examples, x is 6. In some examples, x is 6.5. In otherexamples, x is 7. In some examples, x is 7.5. In other examples x is 8.In some examples, y is 0.3. In some examples, y is 0.35. In otherexamples, y is 0.4. In some examples, y is 0.45. In some examples, y is0.5. In other examples, y is 0.55. In some examples, y is 0.6. In otherexamples y is 0.7. In some examples, y is 0.75. In other examples, y is0.8. In some examples, y is 0.85. In other examples y is 0.9. In someexamples, y is 0.95. In other examples, y is 1.0.

In some examples, provided herein is a composition characterized by theempirical formula Li_(7.0)La₃(Zr_(t1)+Nb_(t2)+Ta_(t3))O₁₂+0.35Al₂O₃. Inthis formula, t1+t2+t3=subscript 2 so that the molar ratio of La to thecombined amount of (Zr+Nb+Ta) is 3:2.

In some examples, provided herein is a composition is characterized bythe empirical formula Li₇La₃Zr₂O₁₂.0.35Al₂O₃.

In some of the above examples, A is 5, 6, 7, or 8. In certain examples,wherein A is 7.

In some of the above examples, M′ is Nb and M″ is Ta.

In some of the above examples, E is 1, 1.5, or 2. In certain examples, Eis 2.

In some of the above examples, C and D are 0.

In some examples, provided herein is a composition wherein the molarratio of Garnet:Al₂O₃ is between 0.1 and 0.65. In some examples, theLi:Al ratio is between 7:0.2 to 7:1.3. In some examples, the Li:Al ratiois between 7:0.3 to 7:1.2. In some examples, the Li:Al ratio is between7:0.3 to 7:1.1. In some examples, the Li:Al ratio is between 7:0.4 to7:1.0. In some examples, the Li:Al ratio is between 7:0.5 to 7:0.9. Insome examples, the Li:Al ratio is between 7:0.6 to 7:0.8. In someexamples, the Li:Al ratio is about 7:0.7. In some examples, the Li:Alratio is 7:0.7.

In some examples, provided herein is a composition wherein the molarratio of Garnet:Al₂O₃ is between 0.15 and 0.55.

In some examples, provided herein is a composition wherein the molarratio of Garnet:Al₂O₃ is between 0.25 and 0.45.

In some examples, provided herein is a composition wherein the molarratio of Garnet:Al₂O₃ is 0.35.

In some examples, provided herein is a composition wherein the molarratio of Al to garnet is 0.35.

In some examples, provided herein is a composition wherein thelithium-stuffed garnet is characterized by the empirical formulaLi₇La₃Zr₂O₁₂ and is doped with aluminum.

In some examples, the lithium stuffed garnet is Li₇La₃Zr₂O₁₂ (LLZ) andis doped with alumina. In certain examples, the LLZ is doped by addingAl₂O₃ to the reactant precursor mix that is used to make the LLZ. Incertain other examples, the LLZ is doped by the aluminum in an aluminumreaction vessel that contacts the LLZ. When the LLZ is doped withalumina, conductive holes are introduced which increases theconductivity of the lithium stuffed garnet. In some examples, thisincreased conductivity is referred to as increased ionic (e.g., Li^(t))conductivity.

ii. Catholytes

Catholyte materials suitable for use with the components, devices, andmethods set forth herein include, without limitation, a garnet materialselected from Li_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Ta_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2, 10<F<14, and M′ and M″ are each, independently in eachinstance selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta,or Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein 5<a<7.7; 2<b<4;0≤c≤2.5; 0≤d<2; 0≤e<2, 10<f<14 and Me″ is a metal selected from Nb, Ta,V, W, Mo, or Sb. In some embodiments, the garnet material isLi_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F). In some other embodiments, thegarnet material is Li_(A)La_(B)M′_(C)M″_(D)Ta_(E)O_(F). In otherembodiments, the garnet material is Li_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F).

In the above examples, the subscript value (4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2, 10<F<14) characterize the ratio of reactants used to makethe garnet material. Certain deviations from these reactant ratios maybe present in the garnet products. As used herein, precursors to Garnetrefers to the reactants used to produce or to synthesize the Garnet.

In the above examples, the subscript value (e.g., 4<A<8.5, 1.5<B<4,0≤C≤2, 0≤D≤2; 0≤E<2, 10<F≤13) characterize the ratio of reactants usedto make the garnet material. Certain deviations from these reactantratios may be present in the garnet products. As used herein, precursorsto Garnet refers to the reactants used to produce Garnet.

In the above examples, the subscript values may also include 4<A<8.5,1.5<B<4, C<2, 0≤D≤2; 0≤E<2, 10<F<14. In some examples, C is equal to1.99 or less.

In the above examples, the subscript values may also include 4<A<8.5,1.5<B<4, C<2, 0≤D≤2; 0≤E<2, 10<F≤13. In some examples, C is equal to1.99 or less.

In certain embodiments, the garnet is a lithium-stuffed garnet.

In some embodiments, the garnet is characterizedLi_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein the subscripts arecharacterized by the values noted above.

In some embodiments, the lithium-stuffed garnet is a lithium lanthanumzirconium oxide that is mixed with aluminum oxide. In some of theseexamples, the lithium lanthanum zirconium oxide is characterized by theformula Li_(7.0)La₃Zr₂O₁₂+0.35Al₂O₃, wherein the subscript andcoefficients represent molar ratios that are determined based on thereactants used to make the garnet.

In some embodiments, the ratio of La:Zr is 3:2. In some other examples,the garnet is Li_(7.0)La₃(Zr_(t1)+Nb_(t2)+Ta_(t3))O₁₂+0.35Al₂O₃; wherein(t1+t2+t3=subscript 2) so that the La:(Zr/Nb/Ta) ratio is 3:2.

In some examples, the garnet is Li_(x)La₃Zr₂O₁₂+yAl₂O₃, wherein x rangesfrom 5.5 to 9; and y ranges from 0 to 1. In some examples x is 7 and yis 0.35.

The catholytes set forth herein include, in some embodiments, ahierarchical structure with a lithium conducting garnet scaffold filledwith carbon electron conductive additive, lithium conductive polymerbinder, and active material. The active material loading can be greaterthan 50 volume percent to enable high energy density. In some examples,the garnet is sintered and retains >70% porosity to allow for the volumeof the other components. The disclosures herein overcomes severalproblems associated with the assembly of a solid energy storage device,for example, but not limited to, sintering composite electrodes havingwell developed contact points between particles and reducedparticle-particle electrical resistance, which permits higher currentflow without a significant voltage drop; also preparing methods formaking entire device (electrodes, and electrolyte) in one step; alsopreparation methods for making solid state energy storage devices whicheliminate the need to use a flammable liquid electrolyte, which is asafety hazard in some instances; and methods for FAST sintering films toreduce the process time and expense of making electrochemical devices;and methods for making FAST sintering and densifying components ofelectrode composites without significant interdiffusion or detrimentalchemical reaction.

iii. Free Standing

In some examples, the disclosure sets forth herein a free-standing thinfilm Garnet-type electrolyte prepared by the method set forth herein.Exemplary free-standing thin films are found, for example, in US PatentApplication Publication No. 2015/0099190, published on Apr. 9, 2015,entitled GARNET MATERIALS FOR LI SECONDARY BATTERIES AND METHODS OFMAKING AND USING GARNET MATERIALS, and filed Oct. 7, 2014, the contentsof which are incorporated by reference in their entirety.

In some embodiments, disclosed herein is a free-standing thin filmGarnet-type electrolyte prepared by a method set forth herein.

In some embodiments, the thickness of the free-standing film is lessthan 50 μm. In certain embodiments, the thickness of the film is lessthan 40 μm. In some embodiments, the thickness of the film is less than30 μm. In some other embodiments, the thickness of the film is less than20 μm. In other embodiments, the thickness of the film is less than 10μm. In yet other embodiments, the thickness of the film is less than 5μm.

In some embodiments, the thickness of the film is less than 45 μm. Incertain embodiments, the thickness of the film is less than 35 μm. Insome embodiments, the thickness of the film is less than 25 μm. In someother embodiments, the thickness of the film is less than 15 μm. Inother embodiments, the thickness of the film is less than 5 μm. In yetother embodiments, the thickness of the film is less than 1 μm.

In some embodiments, the thickness of the film is about 1 μm to about 50μm. In certain embodiments, the thickness of the film about 10 μm toabout 50 μm. In some embodiments, the thickness of the film is about 20μm to about 50 μm. In some other embodiments, the thickness of the filmis about 30 μm to about 50 μm. In other embodiments, the thickness ofthe film is about 40 μm to about 50 μm.

In some embodiments, the thickness of the film is about 1 μm to about 40μm. In certain embodiments, the thickness of the film about 10 μm toabout 40 μm. In some embodiments, the thickness of the film is about 20μm to about 40 μm. In some other embodiments, the thickness of the filmis about 30 μm to about 40 μm. In other embodiments, the thickness ofthe film is about 20 μm to about 30 μm.

In some examples, set forth herein is a thin and free standing sinteredgarnet film, wherein the film thickness is less than 50 μm and greaterthan 10 nm, and wherein the film is substantially flat; and wherein thegarnet is optionally bonded to a current collector (CC) film comprisinga metal or metal powder on at least one side of the film.

In some examples, the thin and free standing sintered garnet film hasthickness is less than 20 μm or less than 10 μm. In some examples, thethin and free standing sintered garnet film has a surface roughness ofless than 5 μm. In some examples, the thin and free standing sinteredgarnet film has a surface roughness of less than 4 μm. In some examples,the thin and free standing sintered garnet film has a surface roughnessof less than 2 μm. In some examples, the thin and free standing sinteredgarnet film has a surface roughness of less than 1 μm. In certainexamples, the garnet has a median grain size of between 0.1 μm to 10 μm.In certain examples, the garnet has a median grain size of between 2.0μm to 5.0 μm.

iv. Substrate Bound

In some examples, the films set forth herein include a film that isbound to a substrate that is selected from a polymer, a glass, or ametal. In some of these examples, the substrate adhered to or bound tothe film is a current collector (CC). In some of these examples, the CCfilm includes a metal selected from the group consisting of Nickel (Ni),Copper (Cu), steel, stainless steel, combinations thereof, and alloysthereof. In some of these examples, the film is bonded to a metalcurrent collector (CC) on one side of the film. In yet other examples,the CC is positioned between, and in contact with, two garnet films.

v. Film Dimensions

In some examples, the thin films set forth herein are less than 50 μm inthickness. In some other examples, the thin films set forth herein areless than 45 μm in thickness. In certain examples, the thin films setforth herein are less than 40 μm in thickness. In still other examples,the thin films set forth herein are less than 35 μm in thickness. Insome examples, the thin films set forth herein are less than 30 μm inthickness. In some other examples, the thin films set forth herein areless than 25 μm in thickness. In certain examples, the thin films setforth herein are less than 20 μm in thickness. In still other examples,the thin films set forth herein are less than 15 μm in thickness. Insome examples, the thin films set forth herein are less than 10 μm inthickness. In some other examples, the thin films set forth herein areless than 5 μm in thickness. In certain examples, the thin films setforth herein are less than 0.5 μm in thickness. In still other examples,the thin films set forth herein are less than 0.1 μm in thickness.

In some examples, provided herein is a composition formulated as a thinfilm having a film thickness of about 100 nm to about 100 μm. In certainexamples, the thickness is 50 μm. In other examples, the thickness is 40μm. In some examples, the thickness is 30 μm. In other examples, thethickness is 20 μm. In certain examples, the thickness is 10 μm. Inother examples, the thickness is 5 μm. In some examples, the thicknessis 1 μm. In yet other examples, the thickness is 0.5 μm.

In some of these examples, the films are 1 mm in length. In some otherof these examples, the films are 5 mm in length. In yet other examples,the films are 10 mm in length. In still other examples, the films are 15mm in length. In certain examples, the films are 25 mm in length. Inother examples, the films are 30 mm in length. In some examples, thefilms are 35 mm in length. In some other examples, the films are 40 mmin length. In still other examples, the films are 45 mm in length. Incertain examples, the films are 50 mm in length. In other examples, thefilms are 30 mm in length. In some examples, the films are 55 mm inlength. In some other examples, the films are 60 mm in length. In yetother examples, the films are 65 mm in length. In still other examples,the films are 70 mm in length. In certain examples, the films are 75 mmin length. In other examples, the films are 80 mm in length. In someexamples, the films are 85 mm in length. In some other examples, thefilms are 90 mm in length. In still other examples, the films are 95 mmin length. In certain examples, the films are 100 mm in length. In otherexamples, the films are 30 mm in length.

In some examples, the films are 1 cm in length. In some other examples,the films are 2 cm in length. In other examples, the films are 3 cm inlength. In yet other examples, the films are 4 cm in length. In someexamples, the films are 5 cm in length. In other examples, the films are6 cm in length. In yet other examples, the films are 7 cm in length. Insome other examples, the films are 8 cm in length. In yet otherexamples, the films are 9 cm in length. In still other examples, thefilms are 10 cm in length. In some examples, the films are 11 cm inlength. In some other examples, the films are 12 cm in length. In otherexamples, the films are 13 cm in length. In yet other examples, thefilms are 14 cm in length. In some examples, the films are 15 cm inlength. In other examples, the films are 16 cm in length. In yet otherexamples, the films are 17 cm in length. In some other examples, thefilms are 18 cm in length. In yet other examples, the films are 19 cm inlength. In still other examples, the films are 20 cm in length. In someexamples, the films are 21 cm in length. In some other examples, thefilms are 22 cm in length. In other examples, the films are 23 cm inlength. In yet other examples, the films are 24 cm in length. In someexamples, the films are 25 cm in length. In other examples, the filmsare 26 cm in length. In yet other examples, the films are 27 cm inlength. In some other examples, the films are 28 cm in length. In yetother examples, the films are 29 cm in length. In still other examples,the films are 30 cm in length. In some examples, the films are 31 cm inlength. In some other examples, the films are 32 cm in length. In otherexamples, the films are 33 cm in length. In yet other examples, thefilms are 34 cm in length. In some examples, the films are 35 cm inlength. In other examples, the films are 36 cm in length. In yet otherexamples, the films are 37 cm in length. In some other examples, thefilms are 38 cm in length. In yet other examples, the films are 39 cm inlength. In still other examples, the films are 40 cm in length. In someexamples, the films are 41 cm in length. In some other examples, thefilms are 42 cm in length. In other examples, the films are 43 cm inlength. In yet other examples, the films are 44 cm in length. In someexamples, the films are 45 cm in length. In other examples, the filmsare 46 cm in length. In yet other examples, the films are 47 cm inlength. In some other examples, the films are 48 cm in length. In yetother examples, the films are 49 cm in length. In still other examples,the films are 50 cm in length. In some examples, the films are 51 cm inlength. In some other examples, the films are 52 cm in length. In otherexamples, the films are 53 cm in length. In yet other examples, thefilms are 54 cm in length. In some examples, the films are 55 cm inlength. In other examples, the films are 56 cm in length. In yet otherexamples, the films are 57 cm in length. In some other examples, thefilms are 58 cm in length. In yet other examples, the films are 59 cm inlength. In still other examples, the films are 60 cm in length. In someexamples, the films are 61 cm in length. In some other examples, thefilms are 62 cm in length. In other examples, the films are 63 cm inlength. In yet other examples, the films are 64 cm in length. In someexamples, the films are 65 cm in length. In other examples, the filmsare 66 cm in length. In yet other examples, the films are 67 cm inlength. In some other examples, the films are 68 cm in length. In yetother examples, the films are 69 cm in length. In still other examples,the films are 70 cm in length. In some examples, the films are 71 cm inlength. In some other examples, the films are 72 cm in length. In otherexamples, the films are 73 cm in length. In yet other examples, thefilms are 74 cm in length. In some examples, the films are 75 cm inlength. In other examples, the films are 76 cm in length. In yet otherexamples, the films are 77 cm in length. In some other examples, thefilms are 78 cm in length. In yet other examples, the films are 79 cm inlength. In still other examples, the films are 80 cm in length. In someexamples, the films are 81 cm in length. In some other examples, thefilms are 82 cm in length. In other examples, the films are 83 cm inlength. In yet other examples, the films are 84 cm in length. In someexamples, the films are 85 cm in length. In other examples, the filmsare 86 cm in length. In yet other examples, the films are 87 cm inlength. In some other examples, the films are 88 cm in length. In yetother examples, the films are 89 cm in length. In still other examples,the films are 90 cm in length. In some examples, the films are 91 cm inlength. In some other examples, the films are 92 cm in length. In otherexamples, the films are 93 cm in length. In yet other examples, thefilms are 94 cm in length. In some examples, the films are 95 cm inlength. In other examples, the films are 96 cm in length. In yet otherexamples, the films are 97 cm in length. In some other examples, thefilms are 98 cm in length. In yet other examples, the films are 99 cm inlength. In still other examples, the films are 100 cm in length. In someexamples, the films are 101 cm in length. In some other examples, thefilms are 102 cm in length. In other examples, the films are 103 cm inlength. In yet other examples, the films are 104 cm in length. In someexamples, the films are 105 cm in length. In other examples, the filmsare 106 cm in length. In yet other examples, the films are 107 cm inlength. In some other examples, the films are 108 cm in length. In yetother examples, the films are 109 cm in length. In still other examples,the films are 110 cm in length. In some examples, the films are 111 cmin length. In some other examples, the films are 112 cm in length. Inother examples, the films are 113 cm in length. In yet other examples,the films are 114 cm in length. In some examples, the films are 115 cmin length. In other examples, the films are 116 cm in length. In yetother examples, the films are 117 cm in length. In some other examples,the films are 118 cm in length. In yet other examples, the films are 119cm in length. In still other examples, the films are 120 cm in length.

In some examples, the garnet-based films are prepared as a monolithuseful for a lithium secondary battery cell. In some of these cells, theform factor for the garnet-based film is a film with a top surface areaof about 10 cm². In certain cells, the form factor for the garnet-basedfilm with a top surface area of about 100 cm².

In some examples, the films set forth herein have a Young's Modulus ofabout 130-150 GPa. In some other examples, the films set forth hereinhave a Vicker's hardness of about 5-7 GPa.

In some examples, the films set forth herein have a porosity less than20%. In other examples, the films set forth herein have a porosity lessthan 10%. In yet other examples, the films set forth herein have aporosity less than 5%. In still other examples, the films set forthherein have a porosity less than 3%.

VI. Electrochemical Cells

In some examples, set forth herein is an electrochemical cell having apositive electrode, a negative electrode, and an electrolyte between thepositive and negative electrode, wherein the electrolyte comprises anelectrolyte separator or membrane set forth herein.

In some examples, set forth herein is an electrochemical cell having anelectrolyte separator set forth herein, wherein the electrochemical cellfurther includes a gel electrolyte.

In some examples, set forth herein is an electrochemical cell having anelectrolyte separator set forth herein, wherein the electrochemical cellfurther includes a gel electrolyte between the positive electrode activematerial and the electrolyte separator.

In some examples, gel comprises a solvent, a lithium salt, and apolymer.

In some of these examples, the solvent is ethylene carbonate, propylenecarbonate, diethylene carbonate, methylene carbonate, or a combinationthereof.

In some of these examples, the lithium salt is LiPF₆, LiBOB, or LFTSi.

In some of these examples, the polymer is PVDF-HFP.

In some of these examples, the gel includes PVDF with the solventdioxolane and the salt, lithium bis(trifluoromethane)sulfonimide(LiTFSI), at 1M concentration.

In some examples the polymer is polypropylene (PP), atacticpolypropylene (aPP), isotactive polypropylene (iPP), ethylene propylenerubber (EPR), ethylene pentene copolymer (EPC), polyisobutylene (PM),styrene butadiene rubber (SBR), polyolefins,polyethylene-co-poly-1-octene (PE-co-PO), PE-co-poly(methylenecyclopentane) (PE-co-PMCP), poly methyl-methacrylate (and otheracrylics), acrylic, polyvinylacetacetal resin, polyvinylbutylal resin,PVB, polyvinyl acetal resin, stereoblock polypropylenes, polypropylenepolymethylpentene copolymer, polyethylene oxide (PEO), PEO blockcopolymers, silicone, or the like.

In some of these examples, the gel acetonitrile as a solvent and a 1Mconcentration of a lithium salt, such as LiPF₆.

In some of these examples, the gel includes a dioxolane solvent and a 1Mconcentration of a Lithium salt, such as LiTFSI or LiPF₆.

In certain examples, the gel includes PVDF polymer, dioxolane solventand 1M concentration of LiFTSI or LiPF₆. In some other examples, the gelincludes PVDF polymer, acetonitrile (ACN) solvent and 1M concentrationof LiFTSI or LiPF₆. In some of these examples, the gel has a EC:PCsolvent and a 1M concentration of a Lithium salt, such as LiTFSI orLiPF₆. In some of these examples, the composite and the gel show a lowimpedance of about 10 Ωcm².

In some examples, the gel is a composite electrolyte which includes apolymer and a ceramic composite with the polymer phase having a finitelithium conductivity. In some examples, the polymer is a single ionconductor (e.g., Li⁺). In other examples, the polymer is a multi-ionconductor (e.g., Li⁺ and electrons). The following non-limitingcombinations of polymers and ceramics may be included in the compositeelectrolyte. The composite electrolyte may be selected frompolyethyleneoxide (PEO) coformulated with LiCF₃SO₃ and Li₃N, PEO withLiAlO₂ and Li₃N, PEO with LiClO₄, PEO: LiBF4-TiO₂, PEO with LiBF₄-ZrO₂.In some of these composites, in addition to the polymers, the compositeincludes an additive selected from Li₃N; Al₂O₃, LiAlO₃; SiO₂, SiC,(PO₄)³⁻, TiO₂; ZrO₂, or zeolites in small amounts. In some examples, theadditives can be present at from 0 to 95% w/w. In some examples, theadditives include Al₂O₃, SiO₂, Li₂O, Al₂O₃, TiO₂, P₂O₅,Li_(1.3)Ti_(1.7)Al_(0.3)(PO₄)₃, or (LTAP). In some of these compositeelectrolytes, the polymer present is polyvinylidenefluoride at about 10%w/w. In some of these as composite electrolytes, the composite includesan amount of a solvent and a lithium salt (e.g., LiPF₆). In some ofthese composites, the solvent is ethyl carbonate/dimethyl carbonate(EC/DMC) or any other solvent set forth herein. In some examples, thecomposite includes a solvent useful for dissolving lithium salts. Insome of the composite electrolytes set forth herein, the polymer servesseveral functions. In one instance, the polymer has the benefit ofameliorating interface impedance growth in the solid electrolyte even ifthe polymer phase conductivity is much lower than the ceramic. In otherinstances, the polymer reinforces the solid electrolyte mechanically. Insome examples, this mechanical reinforcement includes coformulating thesolid electrolyte with a compliant polymer such as poly paraphenyleneterephthalamide. These polymers can be one of a variety of forms,including a scaffold.

vii. Methods of Making Membrane and Separators

In some examples, set forth herein is method of surface treating anelectrolyte separator, which includes providing chemical precursors tothe electrolyte; calcining the chemical precursors to form a calcinedelectrolyte; providing a slurry comprising the calcined electrolyte;casting a film from the slurry; sintering the film to form a sinteredelectrolyte separator; and surface treating the sintered electrolyteseparator in a reducing atmosphere. In some examples, surface treatingcomprises laser ablating, polishing, polishing in dry room atmosphere,annealing, etching, acid washing, plasma abating, and ozone treating.

In some examples, set forth herein is a method of annealing anelectrolyte separator, including providing chemical precursors to theelectrolyte separator; calcining the chemical precursors in an oxidizingatmosphere to form a calcined electrolyte; providing a slurry comprisingthe calcined electrolyte; casting a film from the slurry; sintering thefilm in a reducing or inert atmosphere to form a sintered electrolyteseparator; and annealing the sintered electrolyte separator in areducing or inert atmosphere.

In some examples, the methods further include milling or mixing thechemical precursors before the calcining step.

In some examples, the methods include an oxidizing atmosphere as Air.

In some examples, the sintering step in the methods herein becomes theannealing step by controlling or changing the reducing or inertatmosphere.

In some examples, the sintering step in the methods herein becomes theannealing step by changing temperature of the sintered electrolyteseparator.

In some examples, the chemical precursors are garnet chemicalprecursors.

The method of claim 38 or 39, wherein the annealing comprises heatingthe sintered electrolyte from 200° C. to 1000° C. In some examples, theheating is to 210°, 220°, 230°, 240°, 250°, 260°, 270°, 280°, 290°,300°, 310°, 320°, 330°, 340°, 350°, 360°, 370°, 380°, 390°, 300°, 410°,420°, 430°, 440°, 450°, 460°, 470°, 480°, 490°, 400°, 510°, 520°, 530°,540°, 550°, 560°, 570°, 580°, 590°, 500°, 210°, 620°, 630°, 640°, 650°,660°, 670°, 680°, 690°, 700°, 710°, 720°, 730°, 740°, 750°, 760°, 770°,780°, 790°, 800°, 910°, 920°, 930°, 940°, 950°, 960°, 970°, 980°, 990°,or 1000° Celsius (C),

In some examples, the annealing comprises heating the sinteredelectrolyte from 500° C. to 800° C. In some examples, the annealingcomprises heating the sintered electrolyte from 600° C. to 800° C. Insome examples, the annealing comprises heating the sintered electrolytefrom 700° C. to 800° C. In some examples, the annealing comprisesheating the sintered electrolyte from 500° C. to 700° C. In someexamples, the annealing comprises heating the sintered electrolyte from500° C. to 600° C. In some examples, the annealing comprises heating thesintered electrolyte from 550° C. to 650° C. The method of claim 39,wherein the annealing comprises heating the sintered electrolyte from600° C. to 700° C.

In some examples, the methods further include laser ablation of theelectrolyte surface in a(n) Ar, N₂, He, and/or O₂ atmosphere.

In some examples, the methods include plasma ablation in Ar, N₂, H₂, Heand/or O₂ environment.

In some examples, the methods include heating the sintered electrolytefrom 200° C. to 1000° C. in an inert atmosphere selected from the groupconsisting of He, Ne, Ar, Xe, N₂, and combinations thereof.

In some examples, the methods include heating the sintered electrolytefrom 200° C. to 1000° C. in an inert atmosphere selected from He, Ne,Ar, Xe, or N₂.

In some examples, the methods include heating the sintered electrolytefrom 200° C. to 1000° C. in an inert atmosphere selected from He:H₂,Ne:H₂, Ar:H₂, Xe:H₂, or N₂:H₂. In some of these examples, the ratio ofthe two gases is 100:0 to 50:50 v/v. In certain examples, In someexamples, the ratio of Ar:H₂ is 100:0 to 50:50 v/v.

In some examples, the annealing includes heating the sinteredelectrolyte from 200° C. to 1000° C. in an Argon:H₂ atmosphere until thetop or bottom surface of the electrolyte does not have a layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof.

In some examples, the annealing further includes cooling the electrolyteat least 10° C./min, in an Air atmosphere to room temperature after thecalcining step.

In some examples, the methods herein further include comprisingdepositing Li metal onto the polished surface within 2 days of theannealing step.

EXAMPLES Example 1 Preparation of Electrolyte Separator

In this example, a lithium stuffed garnet electrolyte separator wasprepared.

Lithium-Stuffed Garnet Powder. Calcined lithium-stuffed garnet powderwas produced by the following series of steps. First, lithium hydroxide(LiOH), aluminum nitrate [Al(NO₃)₃9H₂O], zirconia (ZrO₂), and lanthanumoxide (La₂O₃) were massed (i.e., weighed) and mixed into a combinationwherein the molar ratio of the constituent elements wasLi₇La₃Zr₂O₁₂0.5Al₂O₃. This combination was mixed and milled, usingwet-milling techniques and ZrO₂ milling media, until the combination hada d₅₀ particle size of 100 nm 5 μm. Also included with the milling mediawas a Rhodaline™ dispersant. The milled combination of reactants wasseparated from the milling media after milling to the d₅₀ particle size.The separated milled reactants was then placed in an alumina crucibleand calcined at about nine-hundred degrees Celsius (900° C.) forapproximately six (6) hours in an oven with a controlled oxidizingatmosphere in contact with the calcining reactants. The calcinationprocess burned and/or combusted residual solvents as well as thedispersant, binder, and surfactant. The calcination caused the inorganicreactants to react to form the lithium-stuffed garnet. The calcinedproduct was removed from the alumina crucibles after it cooled to roomtemperature. The product is characterized by a variety of analyticaltechniques, including x-ray powder diffraction (XRD) and scanningelectron microscopy. This product is referred to as calcinedlithium-stuffed garnet and has an empirical formula of approximatelyLi₇La₃Zr₂O₁₂0.5Al₂O₃.

The milled and calcined product were then mixed with a plasticizer, abinder selected from acrylic, polyvinylbuturate (PVB), orpolyvinylacetate (PVA), a solvent selected from THF, IPA, or butanol.The organic components constituted 10-20 weight percent of the slurry.The remainder of the slurry was the solid calcined product.

The slurry mixture was then tape cast using a doctor blade setting of20-400 μm to produce 10-200 μm thin films of calcined but unsinteredlithium-stuffed garnet in combination with surfactants, binders,plasticizers, and dispersants.

The tape cast thin films were allowed to dry. These dry calcined byunsintered thin films are referred to as green films.

The green films were placed between garnet ceramic setter plates andcalcined in an oven filled with an Argon:H₂O mixture (calcination step)followed by an Argon:H₂ mixture and heated to 1200° C. for six (6) hours(sintering step). Setter plates were used as substantially set forth inU.S. Provisional Patent Application No. 62/148,337, filed Apr. 16, 2015,entitled LITHIUM STUFFED GARNET SETTER PLATES FOR SOLID ELECTROLYTEFABRICATION. In some samples, the green films were sintered at atemperature selected from 1100° C., 1125° C., 1150° C., or 1175° C. for6 hours in an oven with a controlled atmosphere in contact with thecalcining reactants.

The sintered films were, for some samples, then stored in anArgon-filled glove box, and, for other samples, were stored in air.

Example 2 Annealing Electrolyte Separators to Remove Surface Species

In this example, a lithium stuffed garnet electrolyte separator was madeaccording to Example 1 and then subsequently annealed to remove surfacespecies which result in an increased ionic impedance in the separator.Also in this example a different sample of a lithium stuffed garnetelectrolyte separator was made according to Example 1 but notsubsequently annealed to remove surface species and instead was exposedto air at room temperature for two hours after being made according toExample 1. The sample which was not annealed is referred to herein asSample A. The sample which was annealed is referred to herein as SampleB.

Following the synthesis described in Example 1, the separator was placedin nickel crucible in a tubular furnace with a controlled atmosphere incontact with the annealing separator. The controlled atmosphere includeda gas phase protection environment. Suitable gas phase protectionenvironments used were Ar, He, Kr, N₂, H₂ and mixtures in both staticand flowing conditions. The pressure was maintained at 1 atmosphere.

The samples were annealed at temperature selected from 350° C. to 900°C. as follows:

Annealing Temperature Annealing Time (hours) 350° C. 12 450° C. 12 550°C. 8 650° C. 2 750° C. 2 850° C. 2 950° C. 2

Example 3 Physical Characterization

In this example, the lithium stuffed garnet electrolyte separators werecharacterized.

Electrolyte samples were prepared using a FEI Helio Focused Ion Beam(FIB) electron microscope. The sample had a thickness less 200 nm forTEM imaging. After sample preparation, the sample was stored in anair-tight (i.e., hermetically sealed) container for transfer to the TEMfor imaging and without exposure to air. A FEI Tecnai G2 F20Transmission electron microscope (TEM) was used for sample imaging forboth bright field and dark field imaging.

Attenuated Total Reflection Fourier Transformed Infrared Resonance(ATR-FTIR) spectrum was collected on a Bruker Alpha FTIR spectrometer.Diamond Optics were used for sample mounting.

X-ray photo-electron spectroscopy (XPS) was conducted a PHI-5600 System,equipped with Al—K X-ray sources. After sample preparation, the samplewas stored in an air-tight (i.e., hermetically sealed) container fortransfer to the XPS instrument for analysis. Annealed samples were notexposed to air prior to analysis.

Cross-section imaging was performed using a FEI Quanta 400F ScanningElectron Microscope (SEM). The cross-section was prepared by fracturingspecimen and followed by a thin layer of Au coating.

As shown in the TEM in FIG. 1, Sample A included an electrolyteseparator 101. This separator has an observable layer 102 on top of theelectrolyte separator 103. As shown in the TEM in FIG. 2, Sample Bincluded electrolyte separator 201. This separator does not have anobservable layer on top of electrolyte separator 202. The Sample B(annealed) does not have the surface species which are present on thesurface of Sample A.

As shown in the XPS spectrum in FIG. 3, the annealed sample B does nothave Li₂CO₃ on the surface. The untreated (i.e., unannealed) sample Ashows a Li₂CO₃ coating on the surface of the electrolyte separator.

As shown in the EPR spectra in FIG. 4, in this example, spin density ofSample B is approximately in the order of 1×10⁻¹⁹/cm³.

As shown in the SEM in FIG. 5, the fracture cross-section imageevidences small and uniform grain sizes in the electrolyte separator.

As shown in the Raman spectra in FIG. 10, Sample A, which was notannealed, shows Raman stretches characteristic of the garnet crystalstructure and can be associated with ZrO₆, LaO₈ and LiO₄ chemical units.Sample B, which was annealed, shows Raman stretches characteristic ofthe garnet crystal structure and can be associated with ZrO₆, LaO₈ andLiO₄ chemical units and additional peaks at 515, 531 cm⁻¹ and 711 cm⁻¹.The additional peaks show enhanced surface features in Sample B whichare observable on account of the removal of the surface species throughthe annealing methods in Example 2.

These results show that electrolyte separators having grain sizesbetween 5 μm and 20 μm, and thicknesses between 80-100 μm, can beprepared by Example 1 and subsequently annealed according to Example 2.Samples produced by Example 1, when exposed to air, have a surface layer(about 2 nm in thickness or more) which includes LiCO₃, LiOH, othersurface species. By annealing these samples according to Example 2,herein, these surface species can be removed.

Example 4 Electrochemical Characterization—EIS

In some examples, a two (2) μm thick metallic Li layer was evaporated onboth side of the electrolyte separator to create electrodes. Theelectrolyte having Li layer(s) thereupon was assembled into anelectrochemical cell housing. EIS Nyquist plots were collected using aBiologic VMP-300 potential-stat using a frequency range of 1 MHz 1 Hz.The bulk and interfacial impedances were determined by the Nyquist plot

FIG. 7 shows an EIS Nyquist plot of a Li-garnet-Li cell for twoelectrochemical cells, one with a Sample A electrolyte separator and theother with a Sample B electrolyte separator. FIG. 6 is a magnifiedimagine of the low impedance (high frequency) portion of the EIS signal.This plot shows that the annealed sample, Sample B, has a resistancewhich is much lower than Sample A, which was not annealed.

Annealing Temperature Mean ASR (80 C.) Mean ASR (50 C.) Annealed SampleB <1 Ω-cm²  <1 Ω-cm2 Not annealed Sample A 30 Ω-cm² 182 Ω-cm2

The ASR values were extrapolated from the EIS measurement at as functionof the testing conditions. ASR measurements at both 50° C. and 80° C.confirmed that interfacial ASR was significantly reduced in those cellshaving Sample B electrolyte separators.

Average lateral conductivity at ambient Standard Deviation Conditiontemperature percentage Annealed Sample B 1.0*10⁻⁴ S/cm 6.6% Not annealedSample A 7.8*10⁻⁶ S/cm 13.3%

The lateral ionic conductivity at ambient temperature (˜22° C.) was alsoimproved by two orders of magnitude on average for those cells havingSample B electrolytes as compared to those cells having Sample Aelectrolytes. Sample B membranes also have a more uniform ionicconductivity across the electrolyte's top or bottom surface as comparedto Sample A membranes. The results herein show that at the same currentdensity and testing conditions, Sample A (unannealed) electrolytes havea higher total impedance and also have voltage instability. The resultsherein show that at the same current density and testing conditions,Sample B (annealed) electrolytes have voltage stability and cycleperformance.

Example 5 Electrochemical Characterization Electrochemical Cycling

In this example, a cell is constructed with two lithium electrodes, oneon either side of the solid state electrolyte which in one sample is aSample A electrolyte and in another sample is a Sample B electrolyte. Aconstant current was applied across the cell for a predetermined amountof time and then reversed for an equal duration. The cells were thencycled at 130° C. at a current density of 2 mA/cm² with a chargethroughput of 4 mAh/cm2/cycle (about 20 μm Li/cycle).

As shown in FIGS. 8, 9A, and 9B, the electrochemical cell which includedthe annealed Sample B as the electrolyte membrane was shown to cycle athigh current density for more cycles than a garnet electrolyte membranehas been cycled to date. This shows that Sample B electrolyte membraneshave a longer cycle life and voltage stability. The voltage stability isevidenced by the flat plateaus in the electrochemical cycling data inFIGS. 8A and 8B.

The cell which included the annealed Sample B as the electrolytemembrane was observed to have a high conductance as evidenced by thetotal overpotential of about 25 mV at a current density of 2 mA/cm².This demonstrates a total resistance of 12.5 Ωcm². This same cell wasalso observed to have a symmetric and flat voltage profile. This showsthat the Sample B electrolyte membrane was cycled reversibly and in astable condition at a high current density of 2 mA/cm². Prior to theinstant disclosure, this high of a current density (>1 mA/cm²) of Li⁺ions, and for this amount of time which included passing more than 10 μmof lithium per cycle, has not been publically demonstrated for this typeof electrolyte membrane.

Example 6 Electrochemical Characterization Electrochemical Cycling

Cells prepared as those cells in Example 5 were tested at variouscurrent densities and failure current density was evaluated. Survivingrates were plotted as function of failure current density. A Weibullcumulative plot was generated based on the failure testing data and isplotted as shown in FIGS. 11 and 12.

The foregoing description of the embodiments of the disclosure has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the claims to the precise forms disclosed.Persons skilled in the relevant art can appreciate that manymodifications and variations are possible in light of the abovedisclosure.

The language used in the specification has been principally selected forreadability and instructional purposes, and it may not have beenselected to delineate or circumscribe the inventive subject matter. Itis therefore intended that the scope of the disclosure be limited not bythis detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thedisclosure, which is set forth in the following claims.

1. An electrolyte separator, having top and bottom surfaces and a bulktherebetween, wherein the bulk has a thickness; wherein the top surfaceor bottom surface length or width is greater than the thickness of thebulk by a factor of ten (10) or more, and the thickness of the bulk isfrom about 10 nm to about 100 μm; wherein the bulk is characterized bythe chemical formulaLi_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Ta_(E)O_(F), orLi_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2, 10<F<13, and M′ and M″ are each, independently in eachinstance selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, andTa; or wherein the bulk is characterized by the chemical formulaLi_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein5<a<7.7;2<b<4;0<c≤2.5;0≤d<2; 0≤e<2, 10<f<13 and Me″ is a metal selectedfrom Nb, Ta, V, W, Mo, and Sb; wherein either the top surface or bottomsurface is characterized as having a layer thereupon, greater than 1 nmand less than 1 μm, comprising a lithium carbonate, lithium hydroxide,lithium oxide, lithium peroxide, a hydrate thereof, an oxide thereof, ora combination thereof.
 2. The electrolyte separator of claim 1, whereinthe bulk is characterized by the formula Li_(x)La₃Zr₂O_(z) y(Al₂O₃),wherein 5≤x≤7.5, 11≤z≤12.25, and 0≤y≤1.
 3. The electrolyte separator ofclaim 1, wherein the top surface or bottom surface length or width isfrom about 100 μm to 100 cm.
 4. The electrolyte separator of claim 2,wherein x is 5, 5.5, 6, 6.5, 7, or 7.5.
 5. The electrolyte separator ofclaim 1, wherein the electrolyte bulk is characterized by the chemicalformula Li₅La₃Zr₂O_(h)0.2(Al₂O₃), Li₅La₃Zr₂O_(h) 0.25(Al₂O₃),Li₅La₃Zr₂O_(h)0.3(Al₂O₃), Li₅La₃Zr₂O_(h)0.35(Al₂O₃),Li₅La₃Zr₂O_(h)0.4(Al₂O₃), Li₅La₃Zr₂O_(h)0.45(Al₂O₃),Li₅La₃Zr₂O_(h)0.5(Al₂O₃), Li₅La₃Zr₂O_(h)0.55(Al₂O₃),Li₅La₃Zr₂O_(h)0.6(Al₂O₃), Li₅La₃Zr₂O_(h)0.65(Al₂O₃),Li₅La₃Zr₂O_(h)0.75(Al₂O₃), Li₅La₃Zr₂O_(h)0.8(Al₂O₃),Li₅La₃Zr₂O_(h)0.85(Al₂O₃), Li₅La₃Zr₂O_(h) 0.9(Al₂O₃),Li₅La₃Zr₂O_(h)0.95(Al₂O₃), Li₅La₃Zr₂O_(h)(Al₂O₃),Li₆La₃Zr₂O_(h)0.2(Al₂O₃), Li₆La₃Zr₂O_(h) 0.25(Al₂O₃),Li₆La₃Zr₂O_(h)0.3(Al₂O₃), Li₆La₃Zr₂O_(h)0.35(Al₂O₃),Li₆La₃Zr₂O_(h)0.4(Al₂O₃), Li₃La₃Zr₂O_(h)0.45(Al₂O₃),Li₆La₃Zr₂O_(h)0.5(Al₂O₃), Li₆La₃Zr₂O_(h)0.55(Al₂O₃),Li₆La₃Zr₂O_(h)0.6(Al₂O₃), Li₆La₃Zr₂O_(h)0.55(Al₂O₃),Li₆La₃Zr₂O_(h)0.7(Al₂O₃), Li₆La₃Zr₂O_(h)0.75(Al₂O₃),Li₆La₃Zr₂O_(h)0.8(Al₂O₃), Li₆La₃Zr₂O_(h)0.85(Al₂O₃),Li₆La₃Zr₂O_(h)0.9(Al₂O₃), Li₆La₃Zr₂O_(h)0.95(Al₂O₃),Li₆La₃Zr₂O_(h)(Al₂O₃), Li₇La₃Zr₂O_(h)0.2(Al₂O₃),Li₇La₃Zr₂O_(h)0.25(Al₂O₃), Li₇La₃Zr₂O_(h)0.3(Al₂O₃),Li₇La₃Zr₂O_(h)0.35(Al₂O₃), Li₇La₃Zr₂O_(h)0.4(Al₂O₃),Li₇La₃Zr₂O_(h)0.45(Al₂O₃), Li₇La₃Zr₂O_(h)0.5(Al₂O₃),Li₇La₃Zr₂O_(h)0.55(Al₂O₃), Li₇La₃Zr₂O_(h)0.6(Al₂O₃),Li₇La₃Zr₂O_(h)0.65(Al₂O₃), Li₇La₃Zr₂O_(h)0.7(Al₂O₃),Li₇La₃Zr₂O_(h)0.75(Al₂O₃), Li₇La₃Zr₂O_(h)0.8(Al₂O₃),Li₇La₃Zr₂O_(h)0.85(Al₂O₃), Li₇La₃Zr₂O_(h)0.9(Al₂O₃),Li₇La₃Zr₂O_(h)0.95(Al₂O₃), or Li₇La₃Zr₂O_(h)(Al₂O₃),Li₇La₃Zr₂O_(h)0.3(Al₂O₃), Li₇La₃Zr₂O_(h)0.35(Al₂O₃),Li₇La₃Zr₂O_(h)0.4(Al₂O₃), Li₇La₃Zr₂O_(h)0.45(Al₂O₃),Li₇La₃Zr₂O_(h)0.5(Al₂O₃), Li₇La₃Zr₂O_(h)0.55(Al₂O₃),Li₇La₃Zr₂O_(h)0.6(Al₂O₃), Li₇La₃Zr₂O_(h)0.65(Al₂O₃),Li₇La₃Zr₂O_(h)0.7(Al₂O₃), Li₇La₃Zr₂O_(h)0.75(Al₂O₃),Li₇La₃Zr₂O_(h)0.8(Al₂O₃), Li₇La₃Zr₂O_(h)0.85(Al₂O₃),Li₇La₃Zr₂O_(h)0.9(Al₂O₃), Li₇La₃Zr₂O_(h)0.95(Al₂O₃), orLi₇La₃Zr₂O_(h)(Al₂O₃); wherein subscript h is a rational number from 11to 12.25 and is selected to maintain charge neutrality.
 6. Theelectrolyte separator of claim 1, wherein the electrolyte bulk of theelectrolyte separator is characterized by a chemical formula differentfrom the top surface or bottom surface of the electrolyte separator. 7.The electrolyte separator of claim 1, wherein the bulk of theelectrolyte separator is characterized by the chemical formulaLi_(x1)La₃Zr₂O₁₂ y(Al₂O₃), wherein 5≤x1≤7.5 and 0≤y≤1; wherein the topsurface or bottom surface or both is/are characterized by the chemicalformula Li_(x2)La₃Zr₂O₁₂ y(Al₂O₃), wherein 5≤x2≤7.5 and 0≤y≤1; whereinx2 is less than x1.
 8. The electrolyte separator of claim 1, whereineither the top surface or bottom surface is characterized as having lessthan a 0.5 μm thick layer thereupon comprising a lithium carbonate,lithium hydroxide, lithium oxide, lithium peroxide, a hydrate thereof,an oxide thereof, or a combination thereof.
 9. The electrolyte separatorof claim 8, wherein either the top surface or bottom surface ischaracterized as having less than a 0.35 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof.
 10. The electrolyte separator of claim 9, wherein either thetop surface or bottom surface is characterized as having less than a0.25 μm thick layer thereupon comprising a lithium carbonate, lithiumhydroxide, lithium oxide, lithium peroxide, a hydrate thereof, an oxidethereof, or a combination thereof.
 11. The electrolyte separator ofclaim 10, wherein either the top surface or bottom surface ischaracterized as having less than a 0.15 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof.
 12. The electrolyte separator of claim 11, wherein either thetop surface or bottom surface is characterized as having less than a 0.1μm thick layer thereupon comprising a lithium carbonate, lithiumhydroxide, lithium oxide, lithium peroxide, a hydrate thereof, an oxidethereof, or a combination thereof.
 13. The electrolyte separator ofclaim 12, wherein either the top surface or bottom surface ischaracterized as having less than a 0.05 μm thick layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof.
 14. The electrolyte separator of claim 1, wherein both the topsurface and bottom surfaces are characterized as having a similarthickness layer thereupon comprising a lithium carbonate, lithiumhydroxide, lithium oxide, lithium peroxide, a hydrate thereof, an oxidethereof, or a combination thereof.
 15. (canceled)
 16. The electrolyteseparator of claim 1, wherein both the top surface and bottom surfacesare characterized as having no secondary phases present on the topsurface or bottom surface, wherein secondary phases are selected fromLiAlO₂, Li₂ZrO₃, LaAlO₃, Li₅AlO₄, Li₆Zr₂O₇, La₂(Li_(x)Al_(1-x))O₄,wherein x is from 0 to 1, or combinations thereof.
 17. The electrolyteseparator of claim 1, wherein both the top surface and bottom surfacesare characterized as having the same thickness layer thereuponcomprising a lithium carbonate, lithium hydroxide, lithium oxide,lithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof.
 18. The electrolyte separator of claim 1, having a Li-metalinterface area specific resistance between 0 and 15 Ωcm² at 60° C. 19.The electrolyte separator of claim 18, wherein the Li-metal interfacearea specific resistance is less than 2 Ωcm² at 60° C.
 20. Theelectrolyte separator of claim 1, wherein the Li-metal interface areaspecific resistance is less than 2 Ωcm² at 25° C.
 21. The electrolyteseparator of claim 1, wherein the Li-metal interface area specificresistance is less than 20 Ωcm² at −25° C.
 22. The electrolyte separatorof claim 1, wherein the separator is a pellet, a film, free-standingfilm, or a monolith.
 23. The electrolyte separator of claim 1, whereinthe lithium carbonate is characterized by Li_(x)(CO₃)_(y) and x is from0 to 2, and y is from 0 to
 1. 24. The electrolyte separator of claim 1,wherein the lithium hydroxide is characterized by Li_(x)(OH)_(y) and xand y are each, independently, from 0 to
 1. 25. The electrolyteseparator of claim 1, wherein the lithium oxide is characterized byLi_(x)O_(y) and x and y are each, independently, from 0 to
 2. 26. Theelectrolyte separator of claim 1, wherein the electrolyte separator ischaracterized by an EPR spectrum having a spin density of approximatelyin the order of 1×10⁻¹⁸/cm³ to 1×10⁻²⁰/cm³.
 27. The electrolyteseparator of claim 1, wherein the top surface or bottom surface ischaracterized by an FT-IR spectrum substantially absent of peakscorresponding to Li₂CO₃.
 28. The electrolyte separator of claim 1,wherein the top surface or bottom surface is characterized by a Ramanspectrum having stretches characteristic of the garnet crystal structureand associated with ZrO₆, LaO₈ and LiO₄ chemical units and additionalpeaks at 515, 531 cm⁻¹ and 711 cm⁻¹.
 29. (canceled)
 30. The electrolyteseparator of claim 1, wherein the top surface or bottom surface is indirect contact with Li-metal.
 31. The electrolyte separator of claim 1,having a top surface or bottom surface that has a carbon concentrationat the surface of less than 5 atomic %.
 32. The electrolyte separator ofclaim 1, having a top surface or bottom surface that has a hydrogenconcentration at the surface of less than 5 atomic %.
 33. Theelectrolyte separator of claim 31, wherein the atomic % of carbon ismeasured by XPS.
 34. The electrolyte separator of claim 32, wherein theatomic % of hydrogen is measured by SIMS.
 35. The electrolyte separatorof claim 1, having an oxygen (O) vacancy concentration characterized byan EPR signal spin density of 1×10⁻¹⁸/cm³ to 1×10⁻²⁰/cm³.
 36. Theelectrolyte separator of claim 35, having a spin density equal to about1×10⁻¹⁹/cm³.
 37. An electrochemical cell comprising a positiveelectrode, a negative electrode, and an electrolyte between the positiveand negative electrode, wherein the electrolyte comprises theelectrolyte separator of claim
 1. 38.-56. (canceled)
 57. A method ofcycling lithium through a solid state lithium ion conducting ceramic,comprising providing an electrolyte separator according claim 1, incontact with a lithium metal anode; applying a pressure of at least 300pounds per square inch (PSI) to the electrolyte separator and anode; andcycling at least 10 μm of lithium metal at a current of at least 1mA/cm² or greater.
 58. A method of cycling lithium through a solid statelithium ion conducting ceramic, comprising providing an electrolyteseparator according to claim 1 in contact with a lithium metal anode;applying a pressure of at least 20 PSI to the electrolyte separator andanode; and cycling at least 20 μm of lithium metal at a current of atleast 2 mA/cm² or greater.
 59. An electrochemical cell comprising theelectrolyte separator of claim 1, wherein the electrochemical cellfurther includes a gel electrolyte.
 60. An electrochemical cellcomprising the electrolyte separator of claim 1, wherein theelectrochemical cell further includes a gel electrolyte between thepositive electrode active material and the electrolyte separator. 61.The electrochemical cell of any one of claims 59-60 wherein the gelcomprises a solvent, a lithium salt, and a polymer.
 62. Theelectrochemical cell of claim 61, wherein the solvent is ethylenecarbonate, propylene carbonate, diethylene carbonate, methylenecarbonate, or a combination thereof.
 63. The electrochemical cell ofclaim 61, wherein the lithium salt is LiPF₆, LiBOB, or LFTSi.
 64. Theelectrochemical cell of claim 61, wherein the polymer is PVDF-HFP. 65.(canceled)
 66. The method of claim 58, comprising applying a pressure ofat least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165,170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235,240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305,310, 315, or 320 PSI to the electrolyte separator and anode.
 67. Themethod of claim 58, comprising applying a pressure of at least 320 PSIto the electrolyte separator and anode. 68.-75. (canceled)
 76. Theelectrolyte separator of claim 5, wherein subscript h is
 12. 77. Theelectrolyte separator of claim 1, made by a process which comprises astep of annealing the top surface or bottom surface at a temperature of350° C. or higher.